No. 2, March, 1921] CYTOLOGY 107 



the disappearance of the pyrenoid, while at the same time the nuclei enter the prophases 

 of division. After the nuclear division is completed, cytokinesis takes place at right angles 

 to the long axis of the cell. The two daughter cells grow in length, and then the nucleus 

 of each divides again, the long axis of the spindles generally lying parallel to the recent line 

 of cleavage. This nuclear division is followed by cell division in each of the daughter cells. 

 Hartmann emphasizes the unusual behavior of the pyrenoid during this process, since in 

 C. elongatum it completely disappears during division and is then formed anew in the daugh- 

 ter cells. In other Volvocales, on the other hand, there is a division of the pyrenoid. The 

 restmg nucleus contains 10-20 small granules that fuse to form ten larger granules which 

 are the chromosomes. This fusion of granules is not in the nature of a reduction division. 

 The origin of the spindle is intranuclear, and it frequently has but one pole in early stages. 

 Nuclear history from the metaphase onward is of the usual type. — Gilbert M. Smith. 



731. Herlant, M. Le cycle de la vie cellulaire. Recherches physiologiques sur la divi- 

 sion de la cellule. (Note preliminaire.) [The cycle of cellular life. Physiological researches 

 on the division of the cell. (Preliminary note.)] Ann. et Bull. Soc. roy. Sc. med. et nat. 

 Bruxelles 4: 112-117. 1920. — The author has sought to determine whether the permeability 

 of the cortical layer of the protoplasm is constant during the entire duration of the cellular 

 cycle. He has observed that the plasma membrane of the egg of the sea urchin is, according 

 to the stage of the cell life, sometimes permeable and sometimes impermeable to salts. The 

 lipoid state (semipermeable) and the albuminoid state (permeable) of the plasma membrane 

 do not co-exist, but succeed each other periodically in the course of the cellular life. The 

 physico-chemical equilibrium of the protoplasm, and not alone that of the cortical layer, 

 depends in part on factors destroyed by the insoluble substances in the lipoids (perme- 

 able phase) and in part on factors destroyed by the solvents of the lipoids (semipermeable 

 phase). These phenomena are in accordance with the emulsion theory of protoplasm. — 

 Henri Micheels. 



732. Kowalski, J. Cineses atypiqes dans les cellules adiposes de larves de Pyrrhocoris 

 apterus L. avec quelques remarques sur le centrosome. [Atypical mitoses in the adipose cells 

 of the larvae of Pyrrhocoris apterus L. with some remarks on the centrosome.] La Cellule 

 30: 83-119. 2 pi. 1915-1919. — Author describes and figures a considerable variety of abnor- 

 mal mitotic phenomena observed in the adipose cells of the larva of Pyrrchocoris. The ab- 

 normalities are of two main types: asymmetrical bipolar figures and multipolar figures. 

 These result in irregular distributions of the chromatin to the daughter cells, the frequent 

 loss of chromosomes in the cytoplasm, unequal cell division, and the formation of hypo- and 

 hyperchromatic cells. Such aberrant behavior is apparently due to two causes — the asymmet- 

 rical bipolar figures, to the mechanical action of the numerous large fat vacuoles; and the 

 multipolar ones, to the disturbing action of a toxin secreted by bacteria which infect the 

 larvae. Cells showing the abnormal phenomena do not return to the embryonic state or 

 divide normally. — The normal resting adipose cell has large fat vacuoles, comparatively scanty 

 cytoplasm, and from 1 to 4 nuclei. The nuclear reticulum stains very faintly. From 7 to 9 

 (sometimes more) chromatic nucleoli are present; the total amount of nucleolar material is 

 about constant in all the nuclei. The chromosomes number 24.— 16 of them are rod-shaped and 

 8 are small and spherical. The latter are diflficult to distinguish from the nucleoli, which 

 appear to contribute to the formation of the chromosomes. — A number of observations on 

 normal and abnormal mitotic phenomena in these cells lead to the following conclusions 

 regarding the centrosome and achromatic figure: The formation of the spindle accompanying 

 the development of the chromosomes is the manifestation of a universal and fundamental 

 condition present in all plant and animal cells dividing mitotically; namely an intense and 

 polarized metabolic interchange between chromatin and cytoplasm, showing itself in the 

 bipolarized arrangement of the fibers of the cytoplasmic reticulum. There are two similar 

 opposed cones of fibers because the metaphase chromosomes are split into two equal masses 

 with equal metabolic actions on the cytoplasm; when the chromatic masses are unequal 

 the cones are unequal, and if for any reason they are more than two in number, the figure 



