504 THOMAS H. BHYCK. 



isation o£ tlie aster on the middle piece, are in opposition 

 to it." 



It has been suggested that the centrosome is the seat of 

 formation of a ferment. Mathews (1901), from the results of 

 his experiments on the eggs of Arbacia, believes that " what- 

 ever the details of the process may prove to be, the essential 

 basis of karyokinetic cell division is the production of localised 

 areas of liquefaction in the protoplasm." "■ Tlie centrosome 

 might be a liquefying enzyme." 



Experiments on this line have been tried, but without 

 definite result. Pieri's results (1899), from which he sup- 

 posed he had obtained a ferment " ovulase," have not been 

 confirmed, Dubois (1900) showed that there was no 

 question of a ferment being obtained by Pieri's methods. 

 He made various experiments on sperm and eggs, from 

 which he concluded that there was evidence of the existence 

 of a " zymase," which he provisionally named " Spermase," 

 in the spermatozoa, and in the e^^r^g a substance, at least 

 modifiable by '' spermase," provisionally named " Ovulase." 

 Spermase cannot enter the eg^ by diffusion or osmosis, but 

 only by a mechanical means, which is the raison d'etre of 

 the spermatozoon. Winkler's experiments (1900) are also 

 inconclusive. He used sperm shaken for half an hour in 

 distilled water and filtered five or six times through three- 

 fold filter-paper. The filtrate was added to sea water, the 

 precaution being taken of keeping the mixture at the same 

 degree of concentration as the sea water. While the sperm 

 in heated sea water produced no results, the liquid caused in 

 the case of Spha^rechinus and Arbacia eggs, though in a rela- 

 tively small number, the beginnings of segmentation. These 

 results may have been due to osmotic influences. 



Loeb (1900) states that up to that date he had found no 

 enzyme save papain which had an effect in causing the egg 

 to segment, and it was uncertain whether this was not due 

 to some accidental constituent of the enzyme preparation used. 

 Gics (1901) made a complete study of the effects of extracts 

 of sperm made by the ordinary metliods for the preparation of 



