ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 135 



Maturation and Fertilisation.* — Dr. P. Poljakoff, in the course of 

 his studies on the biology of the cell, has directed his attention to the 

 sexual elements of the much-investigated Ascaris megalocejphala, and, as 

 the result of his work on this and other forms, puts forward some new 

 conclusions. He finds that the head of the spermatozoon consists 

 chiefly of nucleolar substance, the middle piece contains the lininogen 

 corpuscles, and both are surrounded by an envelope of linin substance, 

 which also forms the tail when this is present. The germinal spot of 

 the egg-nucleus is regarded by the author as a nucleolus (= nuclear 

 corpuscle). He opposes the usual view that the chromatin is of supreme 

 importance in fertilisation or cell-division, and regards the nucleolus 

 (nuclear corpuscle) as the important central organ of the cell. To the 

 linin substance he assigns the power of taking up nutritive substances 

 from the surrounding medium, and believes that the phenomena of fer- 

 tilisation, as well as of cell-division, can all be satisfactorily explained 

 in terms of the cell-physiology, as the result of the nutritive processes 

 within the cell. He re-describes these phenomena from this point of 

 view, some parts of the descriptions, e.g. the emphasis laid on the differ- 

 ences as regards food-material between egg and sperm, following lines 

 already made familiar by others. 



Germinal Vesicle of Amphibian Eggs.f — The late Prof. J. B. 

 Carnoy and H. Lebrun made a series of observations on the nuclei of 

 the eggs of various Anura (species of Bufo, JRana, Ac.), which are pub- 

 lished by the latter author as the second part of a joint memoir on the 

 general subject. In default of a general summary of results by the 

 authors, details may be given for Bufo vulgaris. In it the nuclear coil 

 of the oogonium disappears rapidly to form a number of primary nucleoli, 

 which fuse to form a large nucleolus. This large nucleolus then breaks 

 up (undergoes " resolution ") with the production of " bottle-brush " 

 and plumose figures in the caryoplasm, as well as of scattered secondary 

 nucleoli. These nucleoli become vacuolated, and are resolved with the 

 formation of rods and threads, which give the nucleus temporarily its 

 original reticulated appearance. The resolution of the nucleoli is fol- 

 lowed by the vacuolation of the nucleus, which gradually disappears. 

 Of its nucleoli some eight or nine only are left; these become converted 

 into the chromosomes at the time of the formation of the spindle. The 

 chief points of contrast with the eggs of Urodela, no less than the 

 minor differences occurring among the Anura, are in regard to the exact 

 method in which the process of " resolution " is accomplished. 



Pluriovular Follicles in the Rabbit.; — Ch. Honore has found in 

 the same ovary a number of follicles containing more than one ovum. 

 Cases where two, three, four, or even nine ova were present were seen. 

 The general aspect of these follicles seems to the author to cast doubt 

 upon Stoeckel's explanation that the phenomenon is due to division of 

 an originally single ovum. The occurrence of so large a number as 

 nine is in itself against the hypothesis, and further, the ova contained 

 within one follicle were in such various stages of development as to 



* Arch. Mikr. Anat., lvii. (1900) pp. 9-54 (3 pis.). 



t La Cellule, xvii. (1900) pp. 201-b'o. 



X Arch. Biol., xvii. (1900) pp. 489-97 (1 pi.) 



