Paradise lost: Mitochondrial eve refuted

Being based solely on neontological data, all «unique parent» evolutionary hypotheses, of which «Mitochondrial Eve» is one, fall into the category ofscala naturae. Mathematical treatment of neontological data bases, using cladistic approaches does not confer the status of scientific hypotheses onto such scenarios. Apart from these fundamental problems, such hypotheses are flawed on a number of other bases, including the fact that there is a proportion of parental contribution to mitochondrial lineages, despite widely publicised statements that mithocondrial DNA in mammals is «strictly» maternally inherited. Other weaknesses of «unique mother» hypotheses on that their proponents endeavour to describe the evolution of diploid organisms on the basis of variability in extant haploid organelles, the evolution of which is delinked from that of the diploid organism. A further difficulty is that it is not possible to reconstruct interspecific relationships on the basis of intraspecific variability. There is a general ignorance among proponents of «unique mother» hypotheses regarding the distribution of biological variability on the surface of the globe, a fact which renders the molecular clock inaccurate, and which upsets the simplistic proposal that molecular diversity equates with time. «Unique mother» scenarios are also invalidated by the presence of shared chromosome and other polymorphisms in african great apes and humans at similar percentages in the different lineages, a fact which indicates that these evolving populations did not experience «bottlenecks». These and other difficulties effectively refute the «Mitochondrial Eve» hypothesis, which in any case much resembles creationism of a special kind, in which the offspring of a breeding pair are visualised as belonging to a species different from its parents. Such extreme examples of the punctuational mode of evolution are highly likely to be incorrect.     

Revision des evolutionsdenkens?

My criticism of the »organism-centered concept of evolution« as exposed once again by Bonik et al. (this vol.) refers to its phylogenetic application but not to the underlying basic assumption. The misunderstanding is due to the fact that Bonik et al. do not distinguish between evolutionary theory (which is concerned with general problems) and phylogenetic research. Nobody would deny that organisms are energy converting systems. Variants with increased energetic efficiency will of course be favoured by natural selection. But this premise alone does not allow to reconstitute phylogenetic lineages. Evolutionary success of a given variant is determined by many other factors as, for instance, the presence or absence of certain predators. Therefore phylogenetic research depends largely on circumstantial evidence from compared anatomy. Finally it should be stressed that the elimination of »abnormal ontogenetic stages« does not contribute to phylogenetic transformation. Bonik et al. are wrong when they believe that this kind of internal selection constitutes a new, hitherto neglected element which necessitates a fundamental revision of evolutionary theory.     

Selektion und Evolutionstheorie: Müssen »altdarwinistische Dogmen« durch eine kritische Evolutionstheorie ersetzt werden?

Some authors (mainlyBonik, Gutmann, andPeters) have tried to revise current evolutionary concepts, fraught — in their opinion — with “1paleodarwinistic dogmas”. Some points of their theories are reviewed critically in the present paper: (1) Evolution is of course inimaginable without selection, but an “internal selection” eliminating misshaped embryos has nothing to do with evolution. This is stabilizing selection which reduces genetic variation and would even block evolutionary change completely if it was perfect. When this kind of internal selection was “neglected” by earlier authors, this cannot be qualified as paleodarwinistic dogmatism being in contradiction with the premises of evolutionary theory. — (2) Energetic rationalisation of organisms is certainly an important factor in selection but not an absolute law explaining everything about evolution. There are many adaptive processes resulting in less “economic” formations; e.g. heavy armors like those of tortoises, ankylosaurs, and stegosaurs. Among others, protective functions justify a certain waste of energy. — (3) Comparing organisms with technical machines provides an interesting analogy, but again this cannot be considered as the only possible approach for evolutionary models. »Maschinenanalogie« combined with a generalized »internal selection« (i.e. with the nature of adaptive changes determined by the internal construction of organisms) leads inevitably to an underestimation of selective pressures resulting from the ecologic and biocoenotic context. The simple fact of diverging evolutionary lineages shows that the same species (“machine”) can be improved in different ways under the influence of different external factors.     

The failure of conservation strategies in tropical regions and the need to challenge the “Western World Paradigm”

Conservation strategies for tropical species and habitats are decided largely on the basis of studies and examples made in the temperate regions, especially in North America and Europe. Conservation strategies for tropical species are often thought to fail due to a plethora of «human dimension» reasons. These reasons are external to the natural history and ecology of the target species, being due shortage of funds, education and awareness limits, and institutional corruption in several countries, particularly in the developing countries of Africa and Asia. Although these reasons are certainly important in determining the outcome of the conservation projects, herein we stress that there is a scientific ecological reason behind such failures in tropical ecosystems. Indeed, the ecological «entropy» of the species-rich and niche-packed tropical ecosystems is so much higher than that of North America and Europe that adopting a decision-making process based on relatively simplified (temperate) ecosystems, where a given species typically interacts with a few others, makes the eventual solution very simplistic or even «naive», thus enhancing its chances of failure. We urge that, for the future, conservation policies for tropical regions should be based on experiences designed from more realistic «highly-entropic» species-rich systems, also in the case of those species apparently sharing similar ecological roles as in the temperate regions.     

Attività Fotosintetica di Alghe Marine Nella Grotta Delle Viole (Isola S. Domino - Tremiti)

Abstract

Photosynthetic rates of some algae in the marine cave « Grotta delle Viole » (Is. S. Domino - Tremiti). — The « Grotta delle Viole » is one of the several marine caves located along the calcareous rocky southern littoral of the Island S. Domino (Tremiti) in the Adriatic Sea. Morphologically this cave is a tunnel, which connects the open littoral sea with a little bay. Availing of these environmental factors, we have chosen three stations to measure the photosyn-thetic yield, under completely natural conditions, of algae particularly important for some marine communities, described in an other paper (see, Pignatti S. et al. 1967). In station 1 (fig. 1) we have a biotope with strongly reduced light and in the neighbouring stations 2 and 3, two biotopes exposed to sun-light. We have studied three species living in dark places (« Peyssonelia » cfr. « harveyana », « Palmophyllum crassum » and « Pseudolithophyllum expansum » two of well lighted habitas (« Padina pavonia » and « Dictyota dichotoma » and one of intermediate place (« Codium difforme ») Some information on the optical conditions of the seawater have been obtained with a photoelectric cell, filters were used to measure the red and blue light penetration (Tab. 1, 2). This part of the Adriatic Sea is characterized by high penetration of blue light. In the cave this light is highly predominant. The photosynthetic rates were measured in natural conditions by determining the output in time O₂ using the Winkler method (Tab. 3) and the CO₂ changes by measuring pH-changes in short time intervals with an original method using a submarine incubation cell, of our design, equipped with the electrodes of a pH-meter and a spot-light galvanometer as measure instrument. The data obtained with the latter method have been statistically analized, their significance discussed and reported in Tab. 4. On the basis of the results, the species, which are confined in places with reduced light intensity, show a low but measurable photosynthetic surplus only in their natural habitats, transferred in high-light intensity they show a deficit. This fact can suggest the hypotheses: deactivation of the chlorophyll in green and blue light or competitive inhibition due to the presence of accessory pigments. The species of sunny habitats transferred in low-light intensity show an assimilatory deficit, that in this case, with great probability, is due to the progressive reduction of the photosynthetic process. These considerations explaine also the observed distributions of the species and of the algal communities (fig. 1), since each of them is connected with a light optimum. It seems important moreover to note that here, for the first time, data are given also on photosynthetic activity of Lithothamnia.     

Prokaryotic species are sui generis evolutionary units

Many gene flow barriers associated with genetic isolation during eukaryotic species divergence, are lacking in prokaryotes. In these organisms the processes associated with horizontal gene transfer (HGT) may provide both the homogenizing force needed for genetic cohesion and the genetic variation essential to speciation. This is because HGT events can broadly be grouped into genetic conversions (where endogenous genetic material are replaced with homologs acquired from external sources) and genetic introductions (where novel genetic material is acquired from external sources). HGT-based genetic conversions therefore causes homogenization, while genetic introductions drive divergence of populations upon fixation of genetic variants. The impact of HGT in different prokaryotic species may vary substantially and can range from very low levels to rampant HGT, producing chimeric groups of isolates. Combined with other evolutionary processes, these varying levels of HGT causes diversity space to be occupied by unique groups that are mostly incomparable in terms of genetic similarity, genomic cohesion and evolutionary age. As a result, the conventional, cut-off based metrics for species delineation are not adequate. Rather, a pluralistic approach to prokaryotic species recognition is required to accommodate the unique evolutionary ages and tendencies, population dynamics, and evolutionary fates of individual prokaryotic species. Following this approach, all prokaryotic species may be regarded as unique and each of their own kind (sui generis). Taxonomic decisions thus require evolutionary information that integrates vertical inheritances with all possible sources of genetic heterogeneity to ultimately produce robust and biologically meaningful classifications.     

Tunnelbaue rezenter und fossiler phoronidea

New investigations on tunnel burrows of the recent genusPhoronis Wright have proved clearly their identity with the ichnogenus Talpina v. Hagenow 1840, which was regarded previously to belong to boring sponges, annelids (»worms«) or bryozoa, must be referred to the phylum Phoronidea. Definite fossil records of that group hitherto were still missing. The supposition stressed by the present author (Voigt 1972) that the Talpina burrows might be produced by Phoronids was corroborated by comparisons of recent burrows ofPhoronis within the shells with the Talpina burrows observed frequently in fossil shells or rostra of belemnites. Criteria used for the discrimination of such phoronid burrows from other similar burrowing organisms such as Thallophytes, sponges, bryozoa or »worms« are given. The difficulties existing in taxonomy and discerning different species due to the scarcity of morphological characters of these burrows are emphasized. The burrows in question are known since devonian times, partly under other generic names such as (?) Conchifora G. Müller 1968, Conchotrema Teichert 1945, Graysonia Stephenson 1952, Heteronema Ulrich & Bassler 1904 (replaced by Condranema Bassler 1952) and others, but all of them were not recognized as Phoronidea. Talpina gruberi Mayer 1952, T. eduliformis Quenstedt 1858 and T. ramosa v. Hagenow 1840 and the new ones T. hirsuta n. ichnospec. and T. annulata n. ichnospec. are discussed.     

The cryptopolyploidy (Jaretzky 1928: «verkappte Polyploidie»; Chiarugi 1933: «criptopoliploidia»; Melinossi 1935, 1937: «duplicazione endocromosomica»). A terminological criticism.

Abstract

In the cytological literature and text-books, the term cryptopolyploidy is mainly ignored and sometimes re-interpreted and often wrongly quoted from the point of view of historical accuracy. The paternity over this term should be ascribed to Chiarugi (1933), although Jaretzky (1928a, b), while investigating karyologically two species of the genus Bunias, B. orientalis and B. erucago, first advanced a concept of «verkappte Polyploidie» to indicate the occurrence of chromosomes of enlarged size hypothetically due to fusion of homologous members (Jaretzky's «Sammelchromosomen»). By such homologous chromosome fusion a polyploid karyotype could appear as a diploid karyotype. A pupil of Chiarugi, Roma Melinossi, reinvestigating the two species quoted by Jaretzky, Bunias orientalis and B. erucago, documented a quite different karyological state for these species, cf. Melinossi (1935, 1937), that is the presence of the same karyotype (2n=14) in both species and the occurrence of chromosome of doubled size in B. erucago. Melinossi recognized B. erucago to be the cryptopolyploid species (obviously crypto-tetraploid) and not B. orientalis as assumed by Jaretzky and reinterpreted the chromosomes of doubled size as the result of a «duplicazione endocromosomica» (MELINOSSI, 1937).

Almost contemporaneously a second pupil of Chiarugi, Fernanda Pannocchia-Laj, in a karyo-embryological investigation of some species of the genus Vinca, described the occurrence of another case of cryptopolyploidy (sense Melinossi, that is by «duplicazione endocromosomica»). Besides the minor fact that this latter author spelled the term «criptopoliploidia» also as «criptopoliploidismo», her paper is very remarkable because suggested the probable occurrence of a degree of cryptopolyploidy higher than that of Bunias (crypto-tetraploid), namely the occurrence of «… una entità criptopoliploide con valore superiore al tetraploide, probabilmente ottoploide» (cf. PANNOCCHIA-LAJ, 1938 p. 177, p. 178, Fig. 36: criptottoploide).

On the basis of the results of a comparative karyological study between Vinca minor, V. major and V. difformis, PANNOCCHIA-LAJ ascribed to V. minor the diploid karyotype «2n=46», to V. major the tetraploid karyotype «2n=92», and to V. difformis the cryptopolyploid karyotype «2n=46 (x4?)». Since PANNOCCHIA-LAJ (1938, pp. 184–185), following MELINOSSI (1937), interpreted the origin of cryptopolyploidy as a phenomenon due to «duplicazione endocromosomica», the formula «2n=46 (x4?)» clearly means occurrence of «doppia duplicazione endocromosomica» or «quadruplicazione cromosomica».

The author is personally aware that PANNOCCHIA-LAJ intentionally, for scientific prudence, avoided to include such a terms in her account.

The papers of CHIARUGI, MELINOSSI and PANNOCCHIA-LAJ have been largely ignored by the subsequent cytological literature and the term cryptopolyploidy has been variably quoted or interpreted and also reinvented (cf. HOLT in SPARROW & NAUMAN, 1974)!

From a terminological point of view, there are two sound considerations which suggest a refusal of the term cryptopolyploidy, namely:

- the prefix crypto does not qualify, it only means that such a polyploidy is «not visible» (hidden) by the methods of the observer;

- the choice of the prefix crypto is injustifiable because, the cases of cryptopolyploidy show the general morphology of the relative known polyploid species, that is they are phenotypically polyploids!

Both considerations, together, suggest the refusal of the prefix crypto and the proposal of the neoterm phenopolyploidy (phenotypic polyploidy). Necessarily, the indication of phenopolyploidy is nothing else but a provisional term waiting for a modern reinvestigation of both the crypto-tetraploid Bunias erucago and the crypto-octoploid Vinca difformis.     

Studio Comparativo della Struttura e del Ciclo Biologico di Due Diatomee di Acqua Dolce: Navicula Minima Grun. E Navicula Seminulum Grun.: III. Esame Dei Caratteri di Navicula Minima Grun. E di Navicula Seminulum Grun

Abstract

Comparative study of the structure and of the biological cycle of two fresh water diatoms: « Navicula minima » Grun. and « Navicula seminulum » Grun. III. Examination of the characteristics of « N. minima » Grun. and « N. seminulum » Grun. — After studing separately the Navicula minima Grun. and the Navicula seminulum Grun. the various characteristics of the two have been compared and contrasted for purpose of classification. The form and dimentions of the frustules, the density and the structure of the streaks, the structure of the walls, the life circle, aspects of their growths, and some anomalies, most especially, as regards the streaks were examined. It was found the among such numerous characteristics, only one, that is, the presence of the streaks formed by double rows of pores in N. seminulum rather than of a simple file as in N. minima makes one thinks that, in spite of strong similarities existing between these two Naviculae, they are to be regarded as belonging to e different systematic classes. However, their actual positions in taxonomy May-June be defined by further research into the structures and the variabilities of the frustules of other species of Naviculae similar to those examined.     

Insediamento e Diffusione di Buddleia Davidii Franch

Abstract

«Buddleya davidii» in «Valtellina» (North Italy), its settling and diffusion. — Vegetational areas where «Buddleya davidii» is naturalised in Valtellina are described and the subsequent phases are followed through 18 years.     

On the phylogeny of human morality (ten years later)

Sociobiological explanation of altruism, through theories as such «kin selection», cannot reach the wealth of human morality; it is necessary to add some specific traits in order to explain the human way to ultrasociability. Some of them appear within the classical school of «moral sense», distinguishing between two different levels («motive to act» and «moral criterion») of moral phenomenon. Due to the complexity of criterion level, here we deal with a broad model of human moral phenomenon, proposing three different dominions («motive to act», «personal criterion», «collective values»), and trying to find possible phylogenetic roots of them through a cognitive approach.     

Contributo alla Conoscenza dell'idratazione e della Pressione Osmotica Nelle Specie di Tre Associazioni Forestali delle Marche: I° - L'idratazione

Abstract

Researches on the water content and osmotic pressure in plants of three forest associations in the Marche. I° - The water content. — The main forest associations of the Umbro-Marchigiani Appennines are the Orneto-Quercetum ilicis, the Quercetum pubescentis (s. l.) and the Fagetum. In each of these associations a typical station has been chosen where the most important species have been followed from March to November 1963 in order to determine the seasonal variations of their water content (« T.I. »)expressed as percentage of fresh weight.

The annual curves show that the water content reaches very high levels in the early stages of plant development while it falls to lower levels later in the season when the leaves are full grown. The water content of each species follows a different course and can be considered a specific character. Taking into account the maximum and minimum levels of water content of the three groups of species a « hydric spectrum » has been worked out for the three associations.

The water content of each species has also been calculated as percentage of dry weight (imbibition percentage: « G.I. »).     

Phylogeography of the white-clawed crayfish (Austropotamobius italicus) in Spain: inferences from microsatellite markers

The white-clawed crayfish (Austropotamobius italicus), a cornerstone of Spain’s aquatic ecosystems, was once widely distributed throughout much of the country. Unfortunately, its populations have suffered very strong declines over the last 40 years due to the spread of introduced species (red swamp and signal crayfishes), diseases, habitat loss and other anthropogenic impacts. The present work examines the genetic variation in 23 Spanish and four Italian populations of white-clawed crayfish via the analysis of microsatellite loci. The data show genetic variation in the Spanish populations to be affected by drastic and successive bottlenecks. Notwithstanding, the diversity of these Spanish populations in terms of observed heterozygosity is similar to or even higher than that recorded for other European populations studied using these same markers. North-central Spanish populations are clearly differentiated from the country’s remaining populations; they should be considered distinct management units. Processes occurred in historical and recent times, such as genetic drift and translocations, contribute greatly to this genetic structure. These data provide useful information for conservation of this species, since the preservation of its population structure and genetic variability should be goals for management decisions.     

Is parasite pressure a driver of chemical cue diversity in ants?

Parasites and pathogens are possibly key evolutionary forces driving recognition systems. However, empirical evidence remains sparse. The ubiquitous pioneering ant Formica fusca is exploited by numerous socially parasitic ant species. We compared the chemical cue diversity, egg and nest mate recognition abilities in two Finnish and two UK populations where parasite pressure is high or absent, respectively. Finnish populations had excellent egg and nest mate discrimination abilities, which were lost in the UK populations. The loss of discrimination behaviour correlates with a loss in key recognition compounds (C₂₅-dimethylalkanes). This was not owing to genetic drift or different ecotypes since neutral gene diversity was the same in both countries. Furthermore, it is known that the cuticular hydrocarbon profiles of non-host ant species remain stable between Finland and the UK. The most parsimonious explanation for the striking difference in the cue diversity (number of C₂₅-dimethylalkanes isomers) between the UK and Finland populations is the large differences in parasite pressure experienced by F. fusca in the two countries. These results have strong parallels with bird (cuckoo) studies and support the hypothesis that parasites are driving recognition cue diversity.     

Der Neodarwinismus als axiomatisierbares deduktives System und das Problem der Anpassung und Selektion

In the last decade numerous evolutionary models have been proposed and intensively discussed. Surprisingly, the logical analysis of these different hypotheses is not of great importance in this debate. As a matter of fact, Neodarwinism is a consistent deductive system which is based on few but wellconfirmed axioms. Hence, very often, precise statements and definitions of standpoint can be made. This is exemplified by some repeatedly discussed models concerning the problems of Darwinian »adaptation« and »natural selection« 1. Following the logic of the Neodarwinian theory, extinction can only be the result of overspecialization if some very unusual assumptions are made. 2. The hypothesis of »punctuated equilibrium« GOULD 1982), the »effect hypothesis« (VRBA 1983) and the stochastic evolutionary model SCHOPF 1979) include elements which are logically inconsistent with the »modern synthesis«; they could be »true« only if at least one of the neodarwinian axioms (so far not disproved) is negated.     

Inibizione Da Saccarosio Della Demolizione Delle Riserve Lipidiche in Cucurbita Maxima

Abstract

Inhibition by sucrose of utilization of storage lipids in germinating seeds of «Cucurbita maxima». – Previous work demonstrated that sugars inhibit almost completely the respiratory utilization of lipid in isolated cotyledons from germinating «Ricinus communis» seeds as well as in a yeast, «Rhodotorula gracilis». This research was carried out with the aim to further characterize this phenomenon; the material used are the cotyledons and the embryonic axes of «Cucurbita maxima» var. «mammouth», where the lipid contents markedly decrease during the first 72 hours of germination. By incubating the embrional axes, isolated from 48 hours germinating seeds in 0.1M sucrose it was observed: a) a rise of the R.Q. from 0,65 to 1 which is not due to alchoolic fermentation since no degradation of sucrose to ethanol was detected, b) a marked decrease or a complete inhibition of the utilization of fatty acids. On the contrary, no significant increase of R. Q. occurs, when the cotyledons are incubated in presence of 0.1M sucrose. The metabolic utilization of the fatty acids in «Cucurbita maxima» has been studied by using acetate-2-C¹⁴. Labelled acetate was fed after 30 and 90 minutes of incubation of the embryonic axes in water and, respectively in 0.1M sucrose. The radioactivity in the C0₂ and in total fatty acids fractions was measured 30 minutes after feeding the labelled acetate. It was found that: in the presence of sucrose: a) the incorporation of labelled acetate in fatty acids was increased by about 4396 after 30′ and by 10% after 90′. b) the dissimilation of acetate to CO₂ was decreased by about 5096. These results indicate that sucrose replaces lipids as respiratory material. Experiments with labelled acetate are in agreement with the hypotesis that the inhibition of lipid catabolism by sugars (or some derivative) is due chiefly an enhancement of lipid synthesis. At the same time there is probable an inhibition of fatty acids oxidation.     

Saxifraga Berica (Béguinot) D. A. Webb E Asplenium Lepidum Presl Sui Colli Berici

Abstract

«Saxifraga berica» (Béguinot) D. A. Webb and «Asplenium lepidum» Presl on the «Colli Berici». – We have identified a new association in the small caverns of the calcareous rocks in the hills of the north-eastern zone of the «Colli Berici», rising from the Italian plain near Vicenza. We have adopted for this association the name: ADIANTO-SAXIFRAGETUM BERICAE. This phytocoenose is characterized by the endemic «Saxifraga berica». We have found new stations of this remarkable plant and reported some features of this species to complete the diagnosis of D. A. Webb. In two station of this association we have found also the rare «Asplenium lepidum», new for this region.     

Nuovi Dati Sulla Distribuzione Di Isoétes Malinvernianum in Lomellina

Abstract

New data on the distribution of « Isoëtes malinvernianum » in Lomellina. — The Author relates the discovery of many new stations of Isoëtes malinvernianum in Lomellina (Province of Pavia). Many observations carried out in these new localities and in the most part of the already recorded localities near Novara and Vercelli have allowed him to modify some convincements on the habitat of this well known endemism. So he reports that Isoëtes malinvernianum vegetates not only in the waters of « fontanile » but also in waters of the most different sources, that this species is not solitary but accompanied by many species as Callitriche palustris, Fontinalis antipyretica, Sagittaria sagittifolia, Vallisneria spiralis, Potamogeton crispa and few other species more. Isoëtes malinvernianum, besides, is not damaged by dredge works in the canals and is present not only in morainic soils and in the diluvial soils transformated in ferreto but also in the terraced flood named with old terms as « Terrazziano » or « Diluvium recente » and in the diluvial soils of the « Alluvium ». Now at least it is not possible to ascribe plant communities of which Isoëtes malinvernianum makes part to a well defined association.     

Società Botanica Italiana Congresso Sociale 1982 Parto—12-14 Ottobre Relazioni

Abstract

« Harmomegathy »: a still open problem not yet well-known. - Wodehouse used the term « Harmomegathy » to indicate the form and volume change in pollen grains, due to water loss or assumption. Roundish and tricolporate grains in the anther become oval and decrease in volume during the dehydration preceeding anthesis. Viceversa during rehydration on the stigma they undergo the opposite process.

Pollen water content at an thesis varies from species to species and it usually ranges between 10 and 20%; nevertheless in some families as Zingiberaceae and Araceae it is higher. Anther and pollen dehydrations are affected by environmental factors, such as humidity of air and temperature, before the anthesis and when pollen is suspended in air. Besides, to avoid the further loss of water during pollen flow, an oily layer derived from tapetum degeneration is deposited outside the pollen grains.

During dehydration and rehydration pollen grains undergo a stress due to shape and volume changes expecially in the colpus and/or pore areas. Pollen walls are structured in order to avoid their own damage, which could be followed by protoplast death and/or irregularities in grain shape. Intine, formed by pectocellulosic filaments, has elastic properties, as sporopollenin, the component of exine.

Stigma can be dry or wet, namely covered or not by stigmatic exudate giving place to different hydration patterns. The structure of intine and exine has to match that of the stigma, in fact pollen will find the best place and way to proper hydration only on stigmas of its own species. Grains structure also must be sterically conform to stigma: this is well-shown in species as Linum, Lytrum and Primula which have an heteromorphic autoincompatibility.

The right keeping of shape and structure of grains, despite the hydration and dehydration, is therefore essential to the physical-morphological recognition between pollen and stigma, which preceedes the biochemical recognition.     

Sulla Terminologia dei Processi Apomittici

Summary

The Author observing the great disagreement of the terminology usually adopted for the apomictic phenomena, examines the whole series of the phenomena noted both in regards of the formation of the gametophyte and of the embryo. The forming of the gametophyte is fixed on the base of nature of its original cell, normally a haploid spore or »haplospore« (phenomenon of the »haplospory« following the regular meiosis), rarely a diploid spore or »diplospore« (phenomenon of the »diplospory« following the irregular meiosis, as for instance in the case of restitution nucleus, etc.). The original cell can be at least represented by the same cell that usually is the spore mother cell, whether for the outward causes, or for inward causes is lacking the usual reductional process. For the failure of the meiotic process, such a cell cannot be called »spore«.

A cell of the somatic tissue of the sporophyte can even become the original cell of the gametophyte always in case of the absence of the meiosis. These two last cases of apospory are respectively called: »somatic apospory« and »gonial apospory« (= germinal apospory) (Chiarugi 1926).

The formation of the embryo is fixed on the base of the nature of the fecundation. The principal phenomena of the fecundation are represented by the following cases: »amphigamy« (or eugamy, or gamy), »semigamy, »pseudogamy«, »apogamy« »parthenogenesis«. The A. uses the term »apogamy« both for the diploid eggs and for the haploid eggs in which the stimulation of the division is produced by the pollen-tube or by male nuclei, in absence of the gamy.

The term »parthenogenesis« is restricted to the division of the haploid or diploid eggs in which the stimulation is not caused by pollen-tube nor even for the great reason, by the male nuclei existing in it.