253 



I 



SUMMARY OF CURRENT RESEARCHES 



EBDATING TO 



ZOOLOGY AND BOTANY 



f PRINCIPALLY INVERTEBRATA AND CRYPTOGAMIA), 



MICEOSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 



a. Em'bryolog'y, Evolution, Heredity, Reproduction, 



and Allied Subjects. 



G-erm-cells of Brook Lamprey. — Peter Okkelberg {Journ. 

 Morphol, 1921, 35, 1-151, 12 pis., 4 figs.). In the American Brook 

 Lamprey {Entosphe/ms irilderi) the germ- cells are segregated very early 

 in the life of the animal, even before the germinal layers are definitely 

 established. They are first recognizable when the mesoderm separates 

 from the endoderm. The definitive germ-cells take their origin from 

 no other source than the primordial germ-cells, and the germ-cells take 

 no part in the formation of somatic structures. Numerous germ-cells 

 are produced which do not become functional. These degenerate and 

 disappear during the process of development. The germ-cells of each 

 gonad are usually of two kinds, those showing a tendency toward rapid 

 division (katabolic) and those showing a tendency for growth (anabolic). 

 The former are regarded as having a male, the latter a female potentiality. 

 The relative proportion of anabolic and katabolic cells determines 

 whether the larva becomes a male or a female individual. Observations 

 seem to warrant the conclusion that each larva of this species carries the 

 potentiality of both sexes, and that sex, therefore, is not irrevocably 

 fixed at fertilization. J. A. T. 



Osmotic Pressure and Egg-membrane in Salmonidae. — J. 



RuNNSTROM {Ada Zoologica, 1920, 1, 321-36). Unhke the eggs of the 



* The Society does not hold itself responsible for the views of the authors 

 of the papers abstracted. The object of this part of the Journal is to present 

 a summary of the papers as actually publislied, and to describe and illustrate 

 Instruments, Apparatus, etc., which are either new or have not been previously 

 described in this country. 



T 



