似哺乳类爬行动物和哺乳类动物脑颅侧壁构造类型的演替

本文对从原始似哺乳爬行动物进化到高级兽类哺乳动物过程中脑颅侧壁所发生的形态演化进行了分析,根据构造上的不同,将这些动物的脑颅侧壁的构造方式划分为四个构造类型,代表四个进化阶段。     

独叶草叶二叉分枝脉序中网结脉和盲脉的形态学研究

对独叶草营养叶二叉分枝脉序及其中的网结脉和盲脉的形态学研究表明：(1)网结脉中2条完全汇合的与靠近脉中完全分离的叶脉之间未发现任何形式的维管束汇合的中间类型及网结脉中具有不同程度的连接脉退化痕迹的事实表明,网结脉不可能由靠近脉产生,相反,由于网结脉中联结脉的退化而形成开放脉;(2)盲脉是通过伴随着齿退化的达齿脉的退化、网结脉中联结脉的间断、非网结脉由分枝处间断三种方式产生的;(3)越裂片脉的出现及其可以形成网结脉的现象表明独叶草营养叶可能曾具有较为复杂的脉序,这种叶脉也呈现出退化的趋势;(4)独叶草营养叶的二叉分枝脉序可能是一种退化性状,而网结脉的出现可能是这种退化过程中的残留痕迹。     

Contribution on the physiological heart growth. (Experimental autoradiographic studies in mice)]

After injections of 3H thymidine or 3H proline, the physiological hearth growth in mice of the CBA strain belonging to various age groups was studied by means of autoradiography. The most important results are the following: The duration of the postnatal growth period is determined by the degree of maturity of the heart at the time of birth. It varies from species to species. 2. In the perinatal developmental phase the percentage of the 3H thymidine-labelled connective-tissue nuclei is higher than that of the muscle nuclei. In this period the connective supporting tissue is considerably strengthened. 3. During the postnatal developmental phase the DNA synthesis in the muscle nuclei aids the preparation of mitoses. After the postnatal duplication of cells the mitotic genes are repressed. The further growth is effected by the increase in weight of the individual fibres. 4. The process of growth is substantially determined by the intracardiac or intramyocardiac pressure and thus by the extension of the muscle fibre. Prior to birth the percentage of the labelled nuclei of muscle cells and connective tissue cells in the right ventricle was higher than in the left ventricular wall. In the postnatal period we observed a shift in the percentage of the labelled cells towards the left ventricular wall. The basis and the median section of the ventricular wall. The basis and the median section of the ventricular wall contain a higher percentage of labelled cells than does the apex cordis. During the first two weeks of live most of the DNA synthesising nuclei of muscle and connective tissue cells are localized in the two inner muscle shells. Later in life no clear distinctions can be demonstrated between the individual ventricular layers.     

The Structure of the Plumule of Nelumbo Nucifera Gaertn. and the Nature of its Scale

The structure of the plumule of Nelumbo nucifera Gaertn. and its feature covered with scale are seldom seen in dicotyledon. The fact that the plumule possesses scale is even more uncommon. This particular phenomenon is investigated by observing the differentiation of the plumule apex and the development of the leaf organs. After the seed is formed, the embryo has two young leaves and a terminal bud covered with scale. In the bud it has already differentiated the 3rd and the 4th leaf primordium and a shoot apex, the differentiation of which is very complex. So the structure of the plumule passes through 4 plastochrons altogether. It is made clear through observation and analysis that, before the 4th leaf primordium is formed, the transforma- tions of the shoot apex of the embryo in each plastochron are fundamentally alike. After the 4th leaf primordium is developed, the shoot apex becomes complex and there appear 3 different active cell regions which become the bases of vegetative bud of the seeding apex. The development of these 3 active cell regions will be stated in “The Structure of the Vegetative Bud of Nelumbo nucifera Gaertn. and the Nature of its Scales.” The apices of the plumule are almost slightly domed in structure. As a rule, their width is from 95 to 107 μ. Their height is from 17 to 20 μ during one plastochron. Before the 3rd leaf initiation, the anatomical structure of apices is examined and the fol- lowing zones may be delimited: zone of tunica initials, zone of corpus initials, peripheral zone, and zone of rib meristems. It is frequently observed that the cell of corpus in subapical peripheral zone develops periclinal division, which is the initial cell of leaf primordium; Procambium will appear before the stage of the appearance of leaf buttress. The apex of the plumule is in an apical position, but when the seedling is formed, as the developing leaves are alternate, the directions of the shoot apex are changed, simultaneously the base part of the leaf encloses the axis, and the adaxial meristem also differentiates the scale which encloses the terminal bud, thus placing the bud in axillary of the leaf and forming a zigzag phenomenon of the axis of the seedling. Above the basal adaxial side of the leaf primordium develops the scale of the plumule with meristem periclinal division of closely attached protoderm as its base. So the scale of the plumule of Nelumbo nucifera Gaertn. and the axillary stipule are of the same origin. To sum up, the scale of the embryo of Nelumbo nucifera Gaertn. is differentiated from the adaxial meristem of the basal part of the leaf primordium, and is the derivative part of the leaf. It has the same function as the coleoptile of the monocotyledon. Whether they are homologous organs or not is still to be investigated.     

松毛虫赤眼蜂两性生殖品系和孤雌产雌品系在不同品种柞蚕卵中的寄生和生长发育表现

【目的】明确两性生殖品系和孤雌产雌品系松毛虫赤眼蜂Trichogramma dendrolimi在不同品种柞蚕Antheraea pernyi卵中的寄生及发育表现,为以柞蚕卵为替代寄主更好地规模化繁育赤眼蜂提供依据。【方法】测定两性生殖品系和孤雌产雌品系雌蜂在6个品种柞蚕卵［抗大(KD)、大四(DS)、高新(GX)、988(NEE)、青大(QD)和特大(TD)］上的寄生率、子代蜂窝蜂数(单窝羽化子代蜂数)和子代蜂雌性比等生物学指标,以及6个品种柞蚕卵的质量指标(单卵湿重、蛋白质含量、总糖含量和甘油三酯含量);利用主成分分析揭示柞蚕卵质量指标与赤眼蜂生物学指标间的相关性。【结果】NEE品种柞蚕卵育出的两性品系松毛虫赤眼蜂子代蜂个体显著大于除KD和QD品种以外的其他柞蚕品种卵育出的两性品系子代蜂。柞蚕品种对两性品系松毛虫赤眼蜂的寄生率、子代蜂窝蜂数和子代蜂雌性比均无显著影响。在孤雌产雌品系松毛虫赤眼蜂中,KD品种柞蚕卵育出的松毛虫赤眼蜂子代蜂窝蜂数最多,显著高于NEE和QD品种育出的子代蜂窝蜂数,但与DS, GX和TD品种育出的子代蜂窝蜂数相比无显著差异。柞蚕品种对孤雌产雌品系松毛虫赤眼蜂的寄生率和子代蜂个体大小均无显著影响。TD品种柞蚕卵的蛋白质含量最高,显著高于除GX品种以外的柞蚕品种。KD品种柞蚕卵的总糖含量和QD品种柞蚕卵的甘油三酯含量最高,均分别显著高于其余柞蚕品种。主成分分析表明,两性品系松毛虫赤眼蜂寄生率、柞蚕卵蛋白质含量和甘油三酯含量均与柞蚕卵总糖含量呈负相关;两性品系松毛虫赤眼蜂子代蜂个体大小和柞蚕卵甘油三酯含量与单卵湿重呈负相关;孤雌产雌品系松毛虫赤眼蜂寄生率和柞蚕卵甘油三酯含量与松毛虫赤眼蜂子代蜂窝蜂数、柞蚕卵总糖含量和单卵湿重呈负相关;孤雌产雌品系松毛虫赤眼蜂子代蜂个体大小和柞蚕卵总糖含量与蛋白质含量呈负相关。【结论】本研究通过筛选适宜两性生殖品系和孤雌产雌品系赤眼蜂繁育的柞蚕卵品种,初步明确了卵内主要营养指标与子代蜂生物学指标间的相关性。研究结果为利用柞蚕卵更好地规模化繁育松毛虫赤眼蜂提供依据与数据支撑。     

ONTOGENY OF THE OPEN DICHOTOMOUS VENATION IN THE PINNA OF THE FERN NEPHROLEPIS

Pray , Thomas r . (U. South. California, Los Angeles.) Ontogeny of the open dichotomous venation in the pinna of the fern Nephrolepis. Amer. Jour. Bot. 47(5) : 319—328. Illus. 1960.–The venation of the pinna of Nephrolepis consists of a midvein and 2 lateral series of dichotomizing veins all of which terminate freely near the margins. The development of the pinna is analyzed with particular attention to the nature of the marginal meristem and the organization of the embryonic pinna as it appears in paradermal section. The arrangement of cells in pinna wings during the period of marginal growth displays a pattern which foreshadows the pattern of the mature venation. In contrast with the development of the leaves of angiosperms, marginal growth continues into a relatively late phase of pinna ontogeny and apparently is active throughout the phases of ontogeny concerned with blocking-out the pathways of procambial differentiation. Thus the pattern of venation appears to be correlated with the manner of activity of the marginal meristem and subsequent orientation of its derivatives. The theoretical aspects of the result of this investigation are discussed in relation to other studies of foliar venation ontogeny.     

Sublingual structures of primates. II. Hominoidea, review, summary and literature

1. In Homo and the great apes (Pongidae) there occurs, besides the plica sublingualis a plica fimbriata at the ventral surface of the tongue. This duplicature of the mucosa does not occur in the Hylobytidae and in the other primates. 2. Some taste buds could be found in the epithelium of the plica sublingualis of the Pongidae. 3. There are many taste buds in the epithelium of the plica fimbriata of the Pongidae. On this sublingual structure there were counted 1776 taste buds in Pongo, 592 in Gorilla and 280 in Pan. A few taste buds could also be found on the plica fimbriata of a human newborn. 4. A glandula apicis linguae occurs in Homo, Pan, Gorilla and Pongo. 5. The fresh saliva of the glandula apicis linguae and the saliva on the floor of the mouth can be tested by the taste buds in the epithelium of the plica fimbriata, of papillae lenticulares and of areae gustatoriae at the ventral surface of the tongue. 6. It might be the function of the sublingual taste buds to taste the fresh saliva as a gradient for the central nervous comparison with the taste of the saliva on the dorsal surface of the tongue. 7. Because of the complete absence of a sublingua in the Platyrrhini and in the Cercopithecinae it is unlikely that the plica fimbriata of Homo and the great apes can be interpreted as a homalogon of the sublingua in the prosimians. 8. Because of the absence of a sublingua in other ordines of the Mammalia (Insectivora, Carnivora, Rodentia, Chiroptera, Ungulata) it is unlikely as well that the sublingua in the prosimians can be interpreted as a homologon of the tongues of the lower vertebrates. The sublingual structures occuring in the Marsupialia have to be investigated. 9. Because of these reasons the new development of the sublingua in the prosimians and the plica fimbriata in the Hominoidea, in complete independence from one another, seems to be a better explanation of the 2 structures and less contradictionary to anatomical and phylogenetic arguments. The different function of both structures in the recent primates gives a hint for the possible reason for their development during the process of evolution.     

Early steps of the conformational change of influenza virus hemagglutinin to a fusion active state: stability and energetics of the hemagglutinin

A conformational change of the homotrimeric glycoprotein hemagglutinin (HA) of influenza virus mediates fusion between the viral envelope and the endosome membrane. The conformational change of the HA ectodomain is triggered by the acidic pH of the endosome lumen. An essential step of the conformational change is the formation of an extended coiled-coil motif exposing the hydrophobic fusion peptide toward the target membrane. The structures of the neutral-pH, non-fusion active conformation of the HA ectodomain and of a fragment of the ectodomain containing the coiled-coil motif are known. However, it is not known by which mechanism protonation triggers the conformational change of the stable neutral-pH conformation of the ectodomain. Here, recent studies on the stability of the HA ectodomain at neutral pH, the energetics of the conformational change toward the fusion-active state and of the unfolding of the HA ectodomain are summarised. A model for the early steps of the conformational change of the HA ectodomain is presented. The model implicates that protonation leads to a partial dissociation of the distal domains of the HA monomers that is driven by electrostatic repulsion. The opening of the ectodomain enables water to enter the ectodomain. The interaction of water with respective sequences originally shielded from contact with water drives the formation of the coiled-coil structure.     

The structure and activity of the hypophysis of Rana temporaria in normal and in experimental conditions

Summary Volumetric, karyometric and histological studies were done on the pars distalis of the hypophysis of Rana temporaria, in normal and in experimental conditions.In the normal pars distalis, a gradient of activity of the P.A.S.-positive cells is described which shows a close relation with the blood supply. This relation strongly suggests the presence of a gradient of humoral factors which would influence the activity of the pars distalis. This gradient is not dependent on the influence of A.F.-positive neurosecretory fibres. In the P.A.S.-negative cells (O.G.-cells) a similar gradient could not be found. In transplants of pars distalis the gradient of activity is absent.There exists a striking difference between autotransplants and homotransplants of pars distalis in the eye, and also between autotransplants on the iris and autotransplants in the cornea.A parallelism between autotransplants of pars distalis on the iris and the pars distalis of animals deprived of their median eminence could be established. In both groups the pars distalis shows a similar decrease in volume. The glandular cells are well differentiated, but show a low activity. This low activity is most pronounced in the P.A.S.-cells. The normal variability in staining of the P.A.S.-cells has diminished: in general, the great majority of the P.A.S.-cells are P.A.S.-purples. The gradient of activity of the pars distalis has disappeared. The seasonal development of the gonads and of the secundary sexual characteristics is absent. This absence is probably not caused by a decrease of the total number of P.A.S.-cells of the pars distalis. It is probably due to the low activity of the P.A.S.-cells, which cannot be ascribed to the absence of the neurosecretory influence of the magnocellular preoptic nuclei.A preliminary note on the gradient of activity of the pars distalis has been published (Dierickx 1963c).     

Basic Principles of a Psychological Analysis in the Theory of Activity

The general psychological theory of activity created by L. S. Vygotsky, A. N. Leontev, A. R. Luria, and their disciples has entered a critical phase in its development. An external sign of the advent of this phase is the increased frequency of discussions of the role of the category of activity in building the conceptual apparatus of psychology. One hears ever more insistently the idea that the category of activity is threatening to become a kind of monster, ready to devour all other psychological concepts [4,14,37,45]A.n internal sign of the advent of this critical phase in the development of the theory of activity is the discrepancy between the tremendous amount of factual material accumulated in the various special areas of psychology in which the theory of activity plays a special role and the initial principles of this theory, formulated very early, when it was just being developed. As a result, a paradox has emerged: a theory engendered by the exigencies of practice is beginning to be perceived as a theory independent of practice. A critical phase in the development of any theory, like a crisis in the development of the life of a child, means the beginning of a new stage in its existence. For such a critical phase to occur, at least the following steps are, I think, necessary. The first step is enumerating the original principles of the theory of activity. The second involves an analysis, through the prism of these original principles, of all the factual material accumulated in the special areas of psychology and in general psychology. This analysis will overcome the discrepancy between the key principles of the theory of activity and the factual material, and will also help to refine and modify those principles. Finally, the third stage is the development of prospects for basic and applied research, i.e., defining the area for the most immediate development of a psychology built on the basis of a general psychological theory of activity.     

A kinematic study of center of mass motions in the hammer throw

Eight highly-skilled hammer throwers were studied using film analysis procedures. The location and velocity of the center of mass (c.m.) of each thrower, hammer and thrower-hammer system were calculated. The vertical component of motion of all three c.m.s followed cyclic patterns with one fluctuation per turn. The fluctuation of the c.m. of the thrower was ahead of that of the hammer by approximately a third of a cycle, and this made the periods of upward vertical acceleration of the system c.m. coincide approximately with the double-support phases. In the horizontal direction, the c.m.s of the thrower and of the hammer followed roughly trochoid patterns as a result of the combination of rotation with forward displacement across the throwing circle. Their rotations were out of synchrony by approximate synchrony with the hammer, or an essentially straight trajectory. The results of this study suggest that the investigation of the hammer throw might be facilitated by the use of a quasi-inertial non-rotating reference frame that follows the general motion of the system c.m. while ignoring its fluctuations within each turn.     

Regulation and Adaptive Evolution of Lactose Operon Expression in Lactobacillus delbrueckii

Lactobacillus delbrueckii subsp. bulgaricus and L. delbrueckii subsp. lactis are both used in the dairy industry as homofermentative lactic acid bacteria in the production of fermented milk products. After selective pressure for the fast fermentation of milk in the manufacture of yogurts, L. delbrueckii subsp. bulgaricus loses its ability to regulate lac operon expression. A series of mutations led to the constitutive expression of the lac genes. A complex of insertion sequence (IS) elements (ISL4 inside ISL5), inserted at the border of the lac promoter, induced the loss of the palindromic structure of one of the operators likely involved in the binding of regulatory factors. A lac repressor gene was discovered downstream of the beta-galactosidase gene of L. delbrueckii subsp. lactis and was shown to be inactivated by several mutations in L. delbrueckii subsp. bulgaricus. Regulatory mechanisms of the lac gene expression of L. delbrueckii subsp. bulgaricus and L. delbrueckii subsp. lactis were compared by heterologous expression in Lactococcus lactis of the two lac promoters in front of a reporter gene (beta-glucuronidase) in the presence or absence of the lac repressor gene. Insertion of the complex of IS elements in the lac promoter of L. delbrueckii subsp. bulgaricus increased the promoter's activity but did not prevent repressor binding; rather, it increased the affinity of the repressor for the promoter. Inactivation of the lac repressor by mutations was then necessary to induce the constitutive expression of the lac genes in L. delbrueckii subsp. bulgaricus.     

Structure and composition of the Bacillus anthracis capsule

Avakyan, A. A. (Academy of Medical Sciences, Moscow, USSR), L. N. Katz, K. N. Levina, and I. B. Pavlova. Structure and composition of the Bacillus anthracis capsule. J. Bacteriol. 90:1082-1095. 1965.-Observations by various methods of light microscopy (phase contrast, dark-field, and fluorescence) revealed the complex structure of the Bacillus anthracis capsule, which changes regularly during the growth cycle of the culture. Special cytological methods of staining the capsule made it possible to study its fine structure, which is not revealed by negative staining with India ink. For example, the capsule shows a membranelike outline, fine transverse lines, and interruptions and transverse septa traversing the entire capsule. By using cytochemical methods, it was found that the capsule has a stratified structure and that the various layers of the capsule differ as to the value of the isoelectric point, metachromatic ability, sensitivity to various enzymes, and, consequently, chemical composition. It was thus shown that the membranelike outline of the capsule consists of peptides and neutral mucopolysaccharides. The middle part of the capsule consists of a complex of substances of both polysaccharide and protein nature, and the inner part consists of acid mucopolysaccharides. Observation of the capsular forms of B. anthracis by means of an electron microscope revealed differences in the osmiophilia and submicroscopic structure of the membranelike outline and the middle and inner parts of the capsule. Immunochemical studies conducted by the fluorescent-antibody method revealed localization of antigens in different parts of the capsule, and made it possible to differentiate the capsular antigens according to their serum-staining ability and according of their relations to enzymes, i.e., their chemical composition. This paper concerns the possibility of studying the fine structure of bacterial capsules in fixed preparations, and the differences and similarities of the antigens of the capsule and cell wall of B. anthracis and of the related species, B. megaterium.     

The effect of haem ligands on the redox states of the hexa-haem nitrite reductase from Wolinella succinogenes.

The nitrite reductase of Wolinella succinogenes containing six covalently bound haem groups has one haem group that will not reduce fully in the presence of excess Na2S2O4. The effect of the extrinsic ligands CO and cyanide on the redox state of this haem was studied by e.p.r. and magnetic c.d. spectroscopy. It was found that both ligands increased the extent of reduction of this haem group, and that in the case of CO binding the level of reduction was correlated with the extent of CO saturation of the enzyme. Stopped-flow studies of the effect of cyanide binding on the rate of dithionite reduction showed that the rate of reduction of the ligand-binding site was increased in the presence of cyanide. This suggests that reduction of the haem groups at the active site is thermodynamically unfavourable in the absence of an extrinsic ligand. The role of the 'non-reducing' haem group and the effect of ligands on this centre and on the rate of reduction are discussed in relation to the reduction of nitrite by this enzyme.     

Evoked potentials of the medulla oblongata of the skate in response to stimulation of lateral line nerves

The characteristics of the bioelectrical reactions of structures of the medulla oblongata connected with lateral line electro- and mechanoreceptor were investigated in acute experiments on skates under urethane anesthesia. The parameters of the evoked potentials (EP) are characteristic of each of the lateral line nerves studied. A comparison of the characteristics of the fast and slow components of the EP obtained by stimulation of nerves of the medulla oblongata makes it possible to state a hypothesis concerning the presynaptic origin of the fast and the postsynaptic origin of the slow components of the EP. A dependence of the magnitude of the EP on the amplitude of the stimulus and on the location of the active electrode was found. The location of the focus of maximum activity was determined for each of the nerves investigated. A correlation was established between some parameters of the bioelectrical reactions of the medulla oblongata and the morphophysiological properties of the fibers which make up the nerves studied. The results obtained make it possible to assume the presence in the medulla oblongata of spatially arranged structures responsible for the development of the bioelectrical effects in response to stimulation of the lateral line nerves of fish.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 3, No. 3, pp. 284–292, May–June, 1971.     

Metabolic relationships of the isolated fractions of the pectic substances of actively growing sycamore cells

1. d-Glucose and l-arabinose serve as precursors of the pectic polysaccharides of sycamore suspension-callus tissue. 2. The rates and characteristics of the incorporation of radioactive sucrose, glucose and mesoinositol by sycamore callus tissue have been compared and shown to be different. 3. The time-course of the incorporation of radioactive glucose into the major fractions within the cells has been determined. Approx. 7-10% of the radioactivity incorporated is present in the whole pectin of the cells. 4. A study of the continuous incorporation of radioactive glucose showed that the neutral arabinan-galactan fraction of the pectin quickly became saturated with the radioactive label. During the incorporation of radioactivity from a pulse of radioactive glucose the neutral fraction became progressively less labelled, with a corresponding increase in the radioactivity of the weakly acidic pectinic acid, which is known to contain neutral sugars. 5. When the cells were exposed to a pulse of radioactive l-arabinose, the label accumulated first in the neutral fraction and then after 4hr. it passed to the weakly acidic pectinic acid with a corresponding decrease in the radioactivity of the neutral fraction. 6. The product that was initially labelled during the first hour of exposure of the cells in the stationary phase to radioactive glucose was identified as an incompletely methylated galacturonan in which the radioactivity was present in the anhydrogalacturonide residues. This polysaccharide probably acts as the precursor of the polyuronide portions of both the strongly acidic and weakly acidic pectinic acids. 7. The observations are discussed in relation to the structure of the pectic substances and their function in cell growth and development. A tentative model for their metabolic relationship is put forward.     

A mechanism of formation of protein-free regions in the red cell membrane: the rupture of the membrane skeleton

The process of rupture and redistribution of the red cell membrane skeleton is analyzed theoretically. Following the emergence of the rupture the spectrin-actin network is redistributed on the cytoplasmic surface of the membrane bilayer. Due to the interaction of the membrane skeleton and integral proteins the redistribution of the spectrin-actin network leads to the release of purely lipid regions of the membrane. The scale of the protein redistribution caused by the rupture of the membrane skeleton and the size of the lipid domains produced depend on the shape of the membrane and the value of the electrical interaction of the membrane proteins. The lipid domains occurring as a result of the rupture and relaxation of the spectrinactin network can spontaneously increase or decrease its area. The criteria determining the conditions which result in the system's evolutions leading to the domain growth have been obtained. The character of the evolution is determined by the shape of the membrane region in which the rupture occurs as well as the relation between the effective linear tension of the rupture boundary and the modulus of elasticity of the spectrin-actin network.     

Differentiation of the Shoot Apex and its Relationship to the Development of the Vegetative Organs in Spring Wheat (Yu-Chung-Hung and Kansu 96) under Conditions of Different Soil Water Contents

1. In each stage of the differentiation of the growing cones of these two varieties of wheat, their morphological characters are the same as of the general wheat, their fourth stage being the sign of the beginning of their reproductive structures. 2. The sequence of the differentiation in the development of spikelets is as follows: first the outer glume, then the inner glume, the lemma of the first flower, the primordium of the first flower, the lemma of the second flower and finally the primordium of second flower, etc.; while it is the palea, the stamens, the pistil and the lodicules for the flower part. 3. The differentiations of the primordiums of stamens and pistil start at the same time as the appearance of the awn. 4. It was found that in Kansu 96 the rate of the differentiation of the growing cones is more rapid, its volume bigger, the number of its spikelets and flowers, the chance of fruitification and its yield higher, than those of Yu-Chung-Hung, but the average individual weight of the grain is lower than that of the latter. 5. The rate of the differentiation of the growing cones will be slowed, and the numbers of spikelets, flowers and grains increased if a high moisture content of soil is present. The shape of the spike is grand and close under irrigation, but under drought it is slender and soft. Although the yield of Yu-Chung-Hung is lower than that of Kansu 96, but it appears to have a higher hydronasty than the latter. 6. It was shown in our investigation that the Kansu 96 appears to be of drought resistance. 7. Under normal conditions and in the same variety, the appearances of the leaf and the node of the stem, and the developmental phases of plants may be suggested as an indication of the differentiation of the growing cones. It is recommended that they can be used as a field crop.     

Effect of metabolic substances of oral Actinomyces on Candida albicans

Actinomyces naeslundii, Actinomyces viscosus and Candida albicans are associated with root cavity. The aim of this study was to determine, in vitro, the effect produced by the metabolic substances elaborated by Actinomyces naeslundii and Actinomyces viscosus on Candida albicans. The strains were isolated of saliva. There were used the double plaque diffusion method (DPDM) and the method of radial diffusion (MRD). The effect of the time of incubation and of different concentrations of metabolic substances elaborated by Actinomyces naeslundii and Actinomyces viscosus on the kinetics of growth of C. albicans were studied. Later, the nature of the substances produced by the two strains of Actinomyces was determined. It was found that there was no inhibition of the growth of C. albicans by A. naeslundii and A. viscosus in the DPDM and the MRD. There was stimulation of the growth of C. albicans by the two strains of Actinomyces when the DPDM was used. In the MRD the results were negative. Metabolic substances produced by both species stimulated the growth of C. albicans in low concentrations but at high concentrations inhibition was observed. The best concentration of the stimulating factor, a protein substance stable to 70 degrees C, corresponds to a dilution of 1/80. The inhibition of the growth of C. albicans was produced by the decrease of the pH, the higher effect being obtained with the dilution 1/5. The metabolic substances produced by A. naeslundii and A. viscosus can have both inhibitory and stimulant effects on C. albicans, according to their concentration. These metabolic interactions would condition the proportion of C. albicans in the oral microbial ecosystems.     

Mechanisms controlling the kinetics in proliferation and differentiation of populations of mouse myeloid leukemic cells in vitro

The kinetics of differentiation and proliferation of clone cells (B24) of mouse myeloid leukemic Ml cells in vitro were studied by quantitative determination of cellular morphology. B24 cells were induced to differentiate into only macrophagelike cells by an inducer of differentiation in conditioned medium (CM) of embryo cells. During cell differentiation, the ratio of the area of the nucleus to that of the cell (N.C.R.) decreased from about 55% to 10%. Decrease in the N.C.R. was used as an index of cell differentiation in analysis of the kinetics of differentiation of cells treated with various concentrations of CM. The results showed that the process of differentiation was promoted by increasing the concentration of CM, and that the transition of the cells from the undifferentiated state to the differentiated state occurred in a stochastic manner. Comparison of these morphometric results with those of autoradiography showed that the labeling index of the cells decreases gradually in association with decrease in the N.C.R. of the cells from 50% to 30%. A stochastic model for the kinetics of proliferation and differentiation of the cells simulated the experimental observations on the production of differentiated cells.