Podophyllotoxin in concentrations of 50 mg/L in the nutrient solution of tissue cultures produces a complete metaphase block. At 50mg/L and 500mg/L the cell shows other toxic effects. Cells become rounded, blebbed, vacuolate, and pycnotic. The severity of response increases with increased concentration of podophyllotoxin and duration of exposure. The type of response and its severity vary with the type of tissue studied. The mouse tissues used in these experiments were: normal fetal skin, testis, mammary adenocarcinoma, teratoma, reticulum cell sarcoma and L-sarcoma.
In the present investigation, the minute structure of the motor cells of Mimosa pudica L. was studied from the cytophysiological and microchemi-cal view-point. The results obtained are summarized below. 1) Each motor cell of the main pulvinus has thin cytoplasm at the periphery of the cell. It can be differentiated by eosin in the living condition. The inside of this cytoplasmic layer is occupied by a colorless central vacuole in which a tannin vacuole is found. Such a structure was analyzable by the application of the plasmolysis and of the centrifugal force. 2) The tannin vacuoles were stained with chrysoidin, methylene blue, neutral red, and brilliant cresyl blue. If the cells previously stained with crysoidin are treated with caffeine solution the several modes of precipitation in the vacuole are found. These modes are mentioned as follows: A-type. Vacuoles stained simply with chrysoidin and free from precipitation. B-type. Vacuoles stained with chrysoidin, having precipitation by caffeine in the centre. C-type. Vacuoles stained with chrysoidin, having diffuse precipitation by caffeine. D-type. Vacuoles indifferent to chrysoidin, having a dense precipitation by caffeine. 3) B-type and C-type vacuoles usually appear in the cells beneath the vascular bundle. The cells in the upper portion contain but little of them. The distribution of these vacuoles is not modified by the stimulus. 4) By vital staining with chrysoidin, methylene blue, neutral red etc. the tannin vacuoles are observable in the living condition. Through these techniques tannin vacuoles after receiving a stimulus seemed to be smaller than those in the anesthetized pulvinus. In the material fixed by chromic acid or potassium bichromate, the tannin substance is detected as brown colour. By this reaction, when a stimulus is given, the tannin was observed to have infiltrated in the cytoplasm. 5) There are many tannin vacuoles in the motor tissue cells of pulvinule in the closed condition. They appear more markedly inside these motor tissue than outside. 6) These vacuoles are stained with chrysoidin, methylene blue, neutral red and brilliant cresil blue, and the precipitation appears when they are treated with caffeine solution. 7) In the motor cells, especially at the inner part of the pulvinule, their thin cytoplasm found at the periphery of the cells is stained by eosin solution like the motor cells of main pulvinus.
1. Meiosis in the cock, Gallus domesticus, normally occurs at night. This was shown by Miller in 1938. 2. Meiosis has been induced in the daytime in Gallus by placing the cock in a pure oxygen environment for an hour. 3. The experiment indicates that cell division in the germ cells occurs at a different oxygen tension from that required for the normal function of mature somatic cells, or a physiological condition of some kind reduces the oxygen supply to the testes in the daytime. In either case, oxygen is necessary for the initiation and maintenance of spermatogenesis.
1) In Spirogyra species used in this investigation, the nucleolus contains the characteristic structure which corresponds with “the organizer track” designated by Godward. 2) This species has about 35 chromosomes, one of which is very long and may act as the nucleolar organizing chromosome. 3) In the late telophase, the long chromosome may organize the pre-nucleolar substance which constitutes the coiled structure, together with the long chromosome within the resting nucleolus. 4) After the serial changes in the ensuing prophase, the pre-nucleolar substance divides into two and is transferred with the chromosomes to the daughter nuclei to form the nucleolus, while the nucleolar ground material disperses at the late prophase. 5) Feulgen's nucleal reaction is exclusively negative throughout the mitosis. 6) In the zygospore nucleus the spirem structure is clearly seen to be contrary with the nucleus of the vegetative cell.
New methods of locating currents and static potentials in living tissues with the aid of vital staining have been reviewed. Some methods allow quantitative estimates about the distribution of preponderantly extracellular molecules and a few extra-cellular ions in the electronegative space, and preponderantly intra-cellular molecules and anions in the positive space. With the progress of physical analysis of minerals by spectroscopic analysis or other new methods, it may be expected that the distribution of stained and unstained molecules and ions in the body may be determined automatically in a semi-quantitative way. In current literature, and in most textbooks of biochemistry excepting part of Abderhalden and Peterfi, the electric fields in filter paper are quite generally reported in a reversed manner. The actual experimental facts demonstrate that the field between R, 0.01 and 0.50 is positive and accumulates negative matter, while the field between Rf 0.50 and 1.00 attracts positive molecules and ions and is itself negative. The application of these corrections and these findings to the fundamental theories of cytology may prove of considerable importance in elaborating the true modus-vivendi of the cell. We are indebted to Mrs. Ellen Auerbach for photographing our material so beautifully.
1. Chromosome changes observed in the nurse-cells of Drosophila ovary do not indicate that endomitosis or simple chromosome reduplication occurs in these cells. The increase in volume which their nuclei exhibit is probably due to an increase in length rather than in number of chromosomes. 2. It is evident that up to a certain stage of development of the nurse-cells their chromosomes behave quite like those in meiotic cells: the homologues synapsize and relationally coil about each other, and then each split into two chromatids. It is suspected that chiasma-formation may also occur. Nothing like an actual meiotic division I, however, has been observed. After the homologues have freed from each other, reticulation of the nucleus follows sooner or later. An increase in nucleolar mass accompanies all these changes.
The present paper deals with the chromosome study in various tissue cells of rat embryos and these in the regenerating liver of adult rats after partial extirpation. The number of chromosomes displays a wide range of variation between 36 and 89 in both cases. Most frequent among them are the cells of the normal diploid complex having 42 chromosomes. The frequent chromosome numbers occurring in the liver cells during restoration are grouped into the following three ranges: the diploid range (36-46 chromesomes), the triploid range (59-68 chromosomes), and the tetraploid range (78-89 chromosomes). Through the course of growth of the embryonic liver, and of restoration of the adult liver after partial extirpation, the cells of the diploid range having 36-46 chromosomes, particularly those containing 42 chromosomes, exist in the highest frequency. This implies that the cells of the diploid range primarily contribute to the growth of the embryonic liver, or to the restoration of the adult liver after extirpation. The mechanism affecting the variation of the chromosome number is considered.