The establishment of frequency dependent limits for electric and magnetic fields and evaluation of indirect effects

Summary The biophysical model described in this paper has been used as basis for the preparation of the German standards which determine and define limits of exposure to electric or magnetic fields below several MHz, including 50/60 Hz. The electric field strength within the tissue is considered decisive for the biological effect in the low frequency range. Threshold values of field strengths and current densities including biological effects are compared. It is possible to establish safe, dangerous and hazardous current density curves as a function of frequency. To define exposure limits, the field strength or current density causing injury should be reduced by a factor exceeding 100 in order to avoid well established biological effects. The electric and magnetic field strengths in the human environment are correlated with the corresponding electric current density induced in the human body. This enables safe, dangerous and hazardous levels of current density in the human body to be correlated with the external electric or magnetic field strength. Additionally to the direct field effects indirect effects must be considered. In the second part of this paper data on touch voltages and currents are summarized and evaluated with regard to their health risk. Furthermore, as an example for indirect effects the interference of electric and magnetic fields with pacemakers is considered.Review article by invitation of the editor     

Starch hydrolysing enzymes in the developing barley grain

Summary The enzymes -amylase (-1, 4-glucan 4-glucanohydrolase, 3.2.1.1), -amylase (-1,4-glucan maltohydrolase, 3.2.1.2) and phosphorylase (-1,4-glucan: orthophosphate glucosyltransferase, 2.4.1.1) were assayed in whole grains of barley throughout the maturation period. -amylase and phosphorylase had peaks of activity between 25 and 30 days after anthesis. On the other hand the activity of -amylase in both the available and latent forms reached a maximum value at 35 days after anthesis which did not decrease thereafter. -amylase activity was also assayed throughout development in the endosperm, aleurone, testa pericarp and embryo. Latent -amylase reached a constant maximum value in endosperm at 35 days but available -amylase reached a peak of activity at 25 days and then declined to zero at 45 days. Only latent -amylase was associated with the aleurone layer and activity rose to a maximum value at 35 days. The testa pericarp had mainly latent -amylase whose activity fell from an early maximum at 21 days to zero at 35 days. No hydrolytic activity was associated with the embryo. The phosphorylase activity was low and mainly associated with the endosperm fraction.     

The skeletal isotopic composition as an indicator of ecological and physiological plasticity in the coral genus<Emphasis Type="Italic"> Madracis</Emphasis>

Three species of the reef coral genus Madracis display skeletal isotopic characteristics that relate to depth, colony topography, and consequently to coral physiology. The joint interpretation of skeletal ¹³C and ¹⁸O provides information on the ecological plasticity and adaptation to depth of a coral species. Isotopic results are most easily understood in terms of kinetic effects, which reduce both ¹⁸O and ¹³C below isotopic equilibrium values, and metabolic effects, which only influence the skeletal ¹³C. Madracis mirabilis is adapted to depths shallower than 20 m, and shows the greatest range in kinetic effects and the strongest metabolic ¹³C enrichments caused by symbiont photosynthesis. Madracis formosa lives deeper than 40 m, and shows a reduced range of kinetic effects and relatively weak metabolic ¹³C enrichments. Madracis pharensis inhabits depths from 5 to >60 m, and does not attain the strength of kinetic effects of either of the other two species, apparently because it is not quite as well adapted to rapid growth at either extreme.     

The effect of chlorpromazine and tetracaine on the rapid axonal transport of neurosecretory material in the hypothalamo-neurohypophysial system of the rat

Summary The effects of chlorpromazine (cpz) and tetracaine (tc) on the rapid axonal transport of neurosecretory material (NSM) in the hypothalamo-neurohypophysial system was investigated. Following subarachnoidal injection of these drugs, the incorporation of (³⁵S) cysteine into proteins of the supraoptic nucleus was slightly depressed. The protein-bound radioactivity in the posterior pituitary was markedly lowered in experimental rats which indicates a partial blockage of the rapid axonal transport of NSM along the hypothalamoneurohypophysial tract. Both cpz and tc induced an increase in the number of mitochondria and profiles of granular endoplasmic reticulum. The axons in the infundibulum and neurohypophysis were enlarged by dammed organelles, indicating a blockage of axonal transport. There was an increased number of microvesicles, often arranged in a crystalloid pattern, in the terminals. The number and distribution of neurotubuli and neurofilaments were not changed. A possible stimulatory effect of cpz on the release of NSM from the neural lobe is assumed Possible mechanisms for the action of mitotic inhibitors, transquilizers and local anesthetics are discussed.The present work was supported by grants from Svenska Livforsäkringsbolags Fond, H. Hiertas stiftelse, Magnus Bergwalls stiftelse, The Swedish Medical Research Council No. B73-12X-2543-05B, Statens naturvetenskapliga forskningsråd No. 2535-8 and from the Medical Faculty, University of Göteborg. We are indebted to Mrs. Margareta Andersson, Mrs. Wally Holmberg, Mrs. Elisabeth Norström and Mrs. Ulla Svedin for excellent technical assistance, and to Miss Gull Grönstedt for careful secretarial work.     

Improved production of ginseng polysaccharide by adding conditioned medium to Panax notoginseng cell cultures

By adding 50% (v/v) filtered culture broth to fresh MS medium, the specific growth rate of Panax notoginseng was increased from 0.046 d–1 to 0.068 d–1, and the polysaccharide production and productivity reached 1.21 g l–1 and 61 mg/(ld), respectively, which were 1.3- and 2.3-fold of the control. Further supplementation of the conditioned medium with sucrose, ammonium, nitrate and phosphate gave a cell density of 13.7 g l–1 and a specific growth rate of 0.086 d–1. Polysaccharide production was 1.65 g l–1 and the productivity was 78 mg/(ld).     

Molecular organization of the human CD3 gene family on chromosome 11q23

The genes encoding three invariant components of the human T-cell antigen receptor, the CD3 , , and chains, are located on human chromosome 11 at band q23. We isolated cosmid clones containing the human CD3 and chain genes in vectors designed for rapid and efficient chromosome walking. The human CD3 gene was located in the region immediately downstream of the CD3 and genes using synthetic oligonucleotide probes and the localization of this gene confirmed by DNA sequencing. Detailed restriction mapping of the CD3 locus demonstrated that all three CD3 subunits are encoded within 60 kb of DNA with the CD3 gene located 26 kb downstream of the CD3 and genes. Analysis of genomic DNA on pulsed field gels using probes isolated from these cosmid clones defined a physical map of 750 kb spanning the CD3 locus on human chromosome 11g23. The CD3 genes thus comprise a multigene family encoding cell surface components important for transmembrane signaling on T lymphocytes. The arrangement of these genes suggest that they may share common regulatory elements for the control of gene expression during T-cell ontogeny.     

The good,the bad and the ugly: science,aesthetics and environmental assessment

The question is raised, whether there are peculiarly scientific values which can be applied in environmental assessment. The use of the expression scientific interest is traced from its 19th century origins to modern British statutes. It is argued that attempts to replace expert judgements by objective scientific criteria (e.g., indices of biodiversity) can never be completely successful. In particular, interest is an aesthetic atribute particularly valued by scientists but incapable of precise measurement. While science provides the best framework for informed judgements on conservation issues, the judgements of scientists are inevitably distinct from their experimental results. Judgements rest on ethical and aesthetic values such as importance and interest, which are essential constituents of the scientific sub-culture, but which are not uniquely scientific.     

A model of associative memory in the brain

A model of associative memory for time varying spatial patterns is proposed and simulated on a digital computer. This is a network composed of many neuron-like elements, and shows an ability for associative memory similar to that of the brain.Suppose a number of sequences of spatial patterns are presented to this network, for example, 12345, ABC, and so on. Then, these patterns are memorized in the network. After that, if any part of one of these sequences, say 23, is presented to the circuit, the rest of the sequence, 45, is recalled following to it. It resembles to such a situation — if we hear a part of a melody which we have memorized in the past, the rest of the melody is recalled even after it is stopped half-way. Although the recalled patterns are not always 100% correct, they are not completely destroyed even if the presented patterns are imperfect.     

Microaerophily

Objections to previous definitions of anaerobiosis and micro-aerophily are discussed, and a new definition of micro-aerophily is proposed. A survey of physiological characteristics of the micro-aerophilic bacterium Campylobacter sputorum spp. bubulus is given, and the concept of micro-aerophily is illustrated by the results of a study on the oxygen metabolism and oxygen sensitivity of this bacterium.     

The structure of two distinct pancreatic amylase genes in mouse strain YBR

The amylase complex on mouse chromosome 3 encodes both salivary and pancreatic amylase. It appears that one active gene is present for salivary amylase, whereas pancreatic amylase in some strains is coded by at least 4, and perhaps by more than 10, genes. Strain YBR is different from other strains in that it produces twice as much salivary amylase. Pancreatic amylase in YBR is present as two different protein forms, A and B, the sum of which amounts to only one-third of that in, for instance, strain A/J. YBR chromosomal DNA was cloned in phage , followed by restriction and heteroduplex analysis of recombinant phages carrying amylase genes. Among 32 phage isolates, 5 carried parts of the salivary amylase sequence. The remaining phage isolates contained pancreatic amylase-like sequences and represented three nonoverlapping genomic regions, i.e., one of 34 kb containing a complete gene, PAN-II; another of 41 kb with a complete but different gene, PAN-I, plus a truncated gene, PAN-1; and finally, one of 23 kb with another truncated gene, PAN-2. Parts of the amino acid sequence of A and B have previously been determined, and we report here the sequencing of a 4-kb DNA fragment from Pan-II which establishes that this gene codes for B.This work was supported by the Danish Natural Science Research Council.     

The cytology of phytophthora infestans

Summary Phytophthora infestans has three kinds of somatic nuclei: an oval shaped nucleus (approx. 3.1×2.7 ) which stains diffusely except for a crescent shaped Feulgen positive cap which stains intensely; a granular nucleus whose contents are organized into a fairly constant number of stained bodies, and, a deeply staining condensed nucleus. The capped nucleus is thought to be metabolic or resting and the granular nucleus is thought to be dividing as it is most commonly found in hyphal tips. Attenuated forms of all three kinds of nuclei are found.Nuclear division is mitotic and intranuclear. Eight—ten chromosomes are seen at metaphase.Sporangia have a mean of 6.3 nuclei which is constant for age and strain of culture. Sporangia become multinucleate as a result of nuclear migration and not by division in the developing sporangium. Zoospores are usually uninucleate.The nuclear cap is persistent throughout nuclear division when it also divides. It is associated with flagella production and nuclear migration and has some of the properties of a blepharoplast.     

“Garden hunting” in the American tropics

Using faunal analysis, this article outlines a coastal mammalian harvesting pattern involving a few terrestrial mammals whose biomass appears to have been greater when associated with man than under natural conditions. Archeological evidence suggests that these animals fed regularly on cultivated crops and were hunted in house gardens and cultivated fields. By concentrating the supply of both carbohydrates and animal protein, garden hunting may have eliminated seasonality and scheduling problems. And because it artificially increased the biomass of selected animals, it may have functioned as a substitute for animal domestication.     

Injury to potato leaves exposed to subzero temperatures in the absence of freezing

Electrolyte leakage was measured in hardened and nonhardened leaves of three potato species, Solanum tuberosum L., S. acaule Bitt. and S. commersonii Dun., and one interspecific cross, Alaska Frostless (S. acaule x S. tuberosum) when exposed to various subzero temperatures. The leaves were undercooled (no ice present) from 0°C to -12.5°C for 45 min and to-4°C for up to 10 d. Regardless of the degree of undercooling no injury was observed in any of the potatoes, hardened or nonhardened, for up to 12 h. After 5 d, however, electrolyte leakage was observed in hardened S. tuberosum, S. acaule and S. commersonii, and in nonhardened Alaska Frostless. After 10 d exposure all potatoes, hardened and nonhardened, showed a significant amount of electrolyte leakage as compared to their controls kept at 0°C for 10 d.Scientific Journal Series Paper No. 13842 of the Minnesota Agricultural Experiment Station, St. Paul, Minn     

The isolation of barley-aleurone protoplasts

Summary A procedure is described for the isolation of large numbers of viable aleurone protoplasts. After treatment with Onozuka cellulase protoplasts were obtained which were surrounded by a thin, Onozuka-resistant wall. These cells were termed spheroplasts. Treatment of spheroplasts with Glusulase digested away the residual wall, yielding naked protoplasts. Measurements of respiration using a Clarke-type oxygen electrode indicated that aleurone cells isolated by this procedure were viable.Work supported by National Science Foundation grant GB-27468.     

“Petite-like” mutants of the petite-negative yeastCandida utilis after treatment with ethidium bromide

Petite-like colonies of the petite-negative yeastCandida utilis were obtained after the cells were treated with the mutagenic agent ethidium bromide (Eth-Br) (25 g/ml). The lack of ability to grow on nonfermentable substrates like glycerol, lactate, and ethanol and the tetrazolium assay revealed the respiratory deficiency of two isolated colonies. The mutation frequency was 30 times higher than spontaneous mutation (3×10^–5). Doubling time (td) and specific growth rate () of petite-like respiration-deficient mutants were studied in complete medium. A td increase of 1.8 times over that of respiration-sufficient parental cells was attributable to the slower division rate of the petite-like cells. Assimilation and fermentation properties showed the absence of respiratory capacity. Petite-like colonies did not grow on nonfermentable carbon sources that parentalC. utilis readily utilize for growing.     

We Do Not Dream of the 3 R's: Implications for the Nature of Dreaming Mentation

This report examines the extent to which dream recall involves the 3 R's (reading, writing, and arithmetic). Two separate studies were done. In the first study, two scorers rated, on a blind basis, a total of 456 written dream reports, available from five previous studies. There was perfect agreement between the two scorers. They agreed that there were no instances of reading, no instances of writing, and one instance of probable calculating in the 456 dreams. The second study was a questionnaire survey. Complete responses were obtained from 240 frequent dreamers (who reported remembering a mean of seven dreams per week). The study examined in two ways the frequency of the 3 R's in their recalled dreams. First, in answer to direct questions as to how frequently they dreamt about each activity, roughly 90% of the respondents reported that they never or hardly ever dreamt about each of four activities: reading, writing, typing, and calculating. In answers to other questions, this group reported spending a mean of six hours per day engaged in these activities. Second, responses as to the relative prominence of six activities (walking, writing, talking with friends, reading, sexual activity, typing) in dreaming versus waking produced two clear groupings of activities. Walking, talking with friends, and sexual activity were each rated almost as prominent in dreaming as in waking whereas the second group consisting of writing, reading, and typing were rated as far more prominent in waking than in dreaming. The two activity groups differed at p < .0001. Thus, the 3 R's appear to occur very infrequently in dreams. These findings are placed in a theoretical frame which suggests that dreaming (compared to waking) deals very little with serial activities characterized by input—rapid-processing—output in which the neural nets function in a feed-forward mode. Rather, dreaming may be characterized by relatively broad or loose connection making in which the nets function more in an autoassociative mode.     

Der „biologische Aufstieg“ und seine Kriterien

Zusammenfassung Die Arbeit stellt die Frage nach den Kriterien des fossil belegten Biologischen Aufstiegs der Organismenwelt, d.h. derjenigen Vervollkommnung, die sich nicht innerhalb des Rahmens eines gegebenen Bauplans hält, wie die Anpassungsvervollkommnung, sondern über verschiedenrangige Baupläne hinweg zu höheren Typen führt, z.B. von den Fischen über die Amphibien und Reptilien zu den Säugern bzw. Vögeln. Ausführlich werden zwei Gruppen von Kriterien besprochen, ihr Inhalt dargelegt und ihre Eindeutigkeit zur Charakterisierung des Biologischen Aufstiegs untersucht. Die erste Gruppe umfasst die Kriterien der zunehmenden Differenzierung und harmonischeren Integration. Diese legen die morphologisch-physiologische Differenzierung oder genauer die Ganzheit der Organismen zugrunde, d.h. ihre Vielheit in der Einheit. Die zweite Kriteriengruppe, nämlich zunehmende Umweltunabhängigkeit und zunehmende individuelle Autonomie, geht von den Beziehungen des Organismus zur Umwelt und zu andern Lebensformen aus und betont die Subsistenz der Individuen, d.h. ihr grösseres oder geringeres Losgelöstsein oder ihre Selbständigkeit. Da nun Ganzheit und Subsistenz die entscheidenden Elemente einer biologischen Definition des Individuums sind, lässt sich sagen, dass der Biologische Aufstieg eines Organismus um so höher ist, je stärker seine Ganzheit und Subsistenz und damit sein Individuumsein ist.Eindeutigkeit kommt allen genannten Kriterien nicht zu. Die Gründe für ihre Unschärfe sind verschiedener Art. Zunächst gibt es noch keine eindeutige und vollständige Definition des biologischen Individuums, so dass sich nicht eindeutig umreissen lässt, was einem Organismus eine stärkere oder weniger starke Individualität verleiht. Dann sind die Linien, über die sich Vervollkommnungen vollziehen und von denen die eine innerhalb des Bauplans bleibt (Anpassungsvervollkommnung), die andere aber über ihn hinausführt (Biologischer Aufstieg) so innig und in so eigenartiger Weise miteinander verflochten, dass sie sich nicht sauber scheiden und in ihren charakteristischen Merkmalen genau beschreiben lassen. Jeder Vertreter eines Bauplans, ganz gleich von welcher Ranghöhe, ist nämlich notwendig in eine Umwelt eingepasst und irgendwie spezialisiert. Es gibt keine Typen mit reinen Bauplanmerkmalen, die nach keiner Richtung hin eine Anpassungsvervollkommnung, sondern nur Merkmale des Biologischen Aufstiegs aufweisen. Schliesslich kennen wir fossil nur die Entfaltung oder Ausgestaltung der Grossbaupläne des Tierreichs, nämlich des Wirbeltierstammes und der verschiedenen Gruppen der Wirbellosen, nicht aber das Interessanteste und Wichtigste, nämlich ihren Biologischen Aufstieg zu der organisatorischen Höhe, mit der sie sich im Silur bzw. im Kabrium bereits vorstellen. Das erst würde einen tieferen Einblick in das Wesen des Biologischen Aufstiegs vermitteln.

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Summary This article deals with the question of the criteria for the biological ascent (Biologischer Aufstieg) of the organic world, resting on fossil evidence. That is, of that improvement which is not only restricted to the framework of a given general structure (Bauplan) as is the improvement of adaptation, but which also leads beyond general structures (Baupläne) of differentiated levels to a higher type,e.g. from the fishes through the amphibians and reptiles to the mammals or birds. Two groups of criteria are discussed at length, their content exposed and their univocity for the characterisation of this biological ascent is examined. The first group includes the criteria of increasing differentiation and more harmonious integration. The basis for these is the morphological-physiological differentiation, or more exactly, the totality of the organisms,i.e., their variety-in-unity. The second group of criteria, increasing independence of environment and increasing individual autonomy, is derived from the relationships of the organism to its environment and to other living forms, and stresses the subsistence of individuals,i.e., their greater or lesser degree of independence or self-sufficiency. Now since totality and subsistence are the decisive elements in a biological definition of the individual, it may be said that the biological ascent of an organism is higher, the more perfect its totality and subsistence and therefore its individuality is.The criteria mentioned are not univocal. The reasons for this lack of clarity are varied. First of all, there is no univocal and complete definition of the biological individual, so that it cannot be exactly stated just what gives an organism a more or less perfect individuality. Then the lines, along which improvements are made, and according to which the one remains within the general structure (improvement of adaptation) and the other goes beyond the general structure (biological ascent), are so intimately and singularly bound together, that they cannot be cleanly distinguished, and their characteristic notes exactly described. For each representative of a general structure, regardless of its level, is necessarily fitted into an environment and somehow or other specialised. There are no types with only notes of the general structure which show in no direction an improvment of adaption, but only the signs of biological ascent. Finally, we only have fossil evidence for the development or deployment of the great general structures (Grossbaupläne) of the animal world, namely that of the vertebrates and of the different groups of invertebrates, not for the most interesting and most important, that is, their biological ascent to the level of organisation with which they are found in the Silurian or Cambrian periods. Only that would give us a deeper insight into the essence of biological ascent.

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Résumé Ce travail pose la question des critères de la progression biologique (Biologischer Aufstieg), d'après les documents fossiles, dans le monde des organismes, c'est-à-dire de ce perfectionnement qui ne s'arrête pas à l'intérieur du cadre d'un phylum (Bauplan) donné, comme le perfectionnement de l'adaptation, mais qui conduit, au-de-là de phylums (Baupläne) de rang différent, à des types supérieurs, par exemple, des Poissons pas les Amphibies et les Reptiles jusqu'aux Mammifères ou aux Oiseaux. Deux groupes de critères y sont recensés en détail, leur contenu est exposé, et on les examine pour voir s'ils caractérisent sans ambiguïté la progression biologique. Le premier groupe comprend les critères de différenciation croissante et d'intégration harmonique. Ils sont fondés sur la différenciation morphophysiologique ou plus exactement sur la totalité des organismes, c'est-à-dire leur multiplicité dans l'unité. Le second groupe de critères, à savoir indépendance croissante du milieu et autonomie individuelle croissante, part des relations de l'organisme au milieu et aux autres formes vivantes et souligne la subsistence des individus, c'est-à-dire leur plus ou moins grande indépendence ou leur stabilité interne. Comme totalité et subsistence sont les éléments décisifs d'une définition biologique de l'individu, on peut dire que la progression biologique d'un organisme est d'autant plus élevée que sa totalité et subsistence et par là son être individuel sont plus accusés.Tous les critères mentionnés ne sont pas uniformes. Les motifs de leur imprécision sont divers. Tout d'abord, il n'y a pas encore de définition unique et complète de l'individu biologique, de sorte qu'on ne peut circonscrire d'une manière univoque ce qui confère à un organisme une individualité plus forte ou moins forte. Ensuite les lignées au-delà desquelles s'accomplissent des perfectionnements, et dont l'une reste intérieur au phylum (perfectionnement de l'adaptation), tandis que l'autre le transcende (progression biologique), sont entrelacées si intimement et d'une façon si particulière qu'elles ne se laissent pas séparer franchement et décrire rigoureusement selon leurs signes distinctifs. Tout représentant d'un phylum, peu importe son palier, est en effet nécessairement inséré dans un milieu et en quelque façon spécialisé. Il n'existe pas des types à caractères phylétiques purs, qui ne montrent dans aucune direction un perfectionnement de l'adaptation, mais seulement des marques caractéristiques de la progression biologique. Enfin nous ne connaissons pas les restes fossiles que le développement ou la formation des grands phylums (Grossbaupläne) du règne animal, à savoir du rameau des Vertébrés et des divers groupes des Invertébrés, mais non pas le plus intéressant et le plus important, leur progression biologique jusqu'au degré d'organisation qu'ils présentent déjà à l'époque du Silurien ou plutôt du Cambrien. C'est cela seulement qui permettrait une vue plus profonde sur la nature de la progression biologique.

     

Mutants of Arabidopsis thaliana with altered phototropism

Thirty five strains of Arabidopsis thaliana (L.) Heynh. have been identified with altered phototropic responses to 450-nm light. Four of these mutants have been more thoroughly characterized. Strain JK224 shows normal gravitropism and second positive phototropism. However, while the amplitude for first positive phototropism is the same as that in the wild-type, the threshold and fluence for the maximum response in first positive phototropism are shifted to higher fluence by a factor of 20–30. This mutant may represent an alteration in the photoreceptor pigment for phototropism. Strain JK218 exhibits no curvature to light at any fluence from 1 mol·m^-2 to 2700 mol·m^-2, but shows normal gravitropism. Strain JK345 shows no first positive phototropism, and reduced gravitropism and second positive phototropism. Strain JK229 shows no measurable first positive phototropism, but normal gravitropism and second positive phototropism. Based on these data, it is suggested that: 1. gravitropism and phototropism contain at least one common element; 2. first positive and second positive phototropism contain at least one common element; and 3. first positive phototropism can be substantially altered without any apparent alteration of second positive phototropism.Abbreviation WT wild-type     

Pancreatic glucagon cells contain endorphin-like immunoreactivity

Summary On the basis of the histochemical activity of succinic dehydrogenase, only two fibre-types are distinguished in pigeon pectoralis major muscle. These are narrow Red and broad White. The histochemical activity of myofibrillar ATPase was studied in these two distinct fibre-types. Both fibre-types showed high activity for the ATPase. Red fibres of pigeon pectoralis were not alkali-labile, at incubation pH 9.4, as were the Type I fibres of both avian and mammalian muscles. Again unlike Type I fibres, the Red fibres of pigeon pectoralis lacked the characteristic activation of acid-preincubated ATPase reaction. Pigeon pectoralis Red fibres are known to posses some characteristics of fast-twitch fibres (e.g. high fat, considerable phosphorylase, fibrillenstruktur myofibrillar arrangement, focal en plaque pattern of nerve endings). It is emphasized, therefore, that the pigeon pectoralis Red fibres are not equivalent to Type I or slow-twitch, muscle fibres, but they are possibly fast-twitch fatigue resistent or Type II Red muscle fibres.