ZOOLOGY 377 



ZOOLOG-Y. By Reginald James Ludford, Ph.D., B.Sc, University 

 College, London. 



Protozoology. — -The physical structure of the protoplasm of 

 Amceba is discussed by H. Giersberg in a paper entitled, " Unter- 

 suchungen zum Plasmabau der Amoben, im Hinblick auf die 

 Wabentheorie " {Archiv fur Entwick. der Organ., July 1922). 

 The writer has carried out a series of investigations on chemical 

 influences on the cytoplasm, on pseudopodia formation and 

 amoeboid movement, and also experiments with Actinosphae- 

 rium. The reticulate structure {wabenstruktur) of Amoeba, he 

 concludes, is only an occasionally appearing physiological 

 condition, and is not the constantly present ground structure 

 of the protoplasm. 



R. Weissenberg describes in the Zoo/. Anz., Bd. Iv, No. 3/4, 

 a myxosporidian-like parasite which occurs in the glomeruli 

 of the kidney of the pike. It was present in eight fish out of 

 twenty-six which were obtained from the Berlin markets 

 during the late winter. 



Cytology and Histology. — The nature of the relationship 

 existing between nuclear and protoplasmic activities is one of 

 the fundamental problems of cytology. It is, therefore, of 

 interest to note a further case of nucleolar extrusions from the 

 nucleus into the cytoplasm, which is described in the oocyte 

 of the water scorpion by E. A. Spaul {Jr. R. Micr. Soc, Sept. 

 1922). This process is said to coincide with the deposition of 

 yolk in the oocyte cytoplasm. The study of the chromosomes 

 in the same insect, during spermatogenesis and oogenesis, has 

 shown that there is a single X-chromosome in the male and 

 a pair in the female, but they are not conspicuous and unable 

 to be identified until cell division takes place. 



J. Bronte Gatenby contributes " Some Notes on the Gameto- 

 genesis of Ornithorhynchus paradoxus " to the Q.J. M.S., 

 vol. Ixvi, Part III, 1922. Probably the most interesting fact 

 ascertained by an examination of this primitive mammal, is 

 the presence of a large hollow cavity in the young ovary. 

 " This is undoubtedly a primitive character, which is noticeable 

 even in the adult ovary, in the form of numerous lacunse 

 throughout the stroma of the ovary." The ovary of the 

 original vertebrate seems to have been a sac-like structure, 

 the stroma being a new formation ; the cells, which in Ornitho- 

 rhynchus constitute this loose stroma, seem to have been formed 

 by a retro-peritoneal invasion," however they never quite 

 fill the cavity even of the adult ovary. 



The discharge of the egg from the ovary differs from that 

 of the placental mammals, being similar to the process occurring 

 in the frog. Yolk-formation resembles that of the bird described 

 bv Van Durme. 



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