SOME PROBLEMS OF RE PRODUCTION. 583 



Some Problems of Reproduction.— II. 



Professor Marcus llartog:, 



Queen's College, Cork. 



A. — Multiple Fission akd Embryonic Enzymes. 



Recent researches on the utilisation of reserves in plants 

 had shown that in every case examined a ferment or enzyme 

 was present which, under suitable circumstances, could effect 

 in vitro the same process, usually of hydrolysis, which the 

 living organism performs. Thus, if the green cell, under the 

 influence of light, accumulates starch as a reserve during the 

 day, and this starch is removed as a soluble sugar during the 

 night, a diastatic ferment can be isolated from these green 

 cells, and Avill operate the same conversion. So, too, from 

 germinating seeds we can extract a peptonising ferment 

 which, like trypsin, will hydrolise proteids into peptones and 

 beyond, yielding leucin, tyrosiu, and other amides, such as 

 asparagin. From this consideration on the one hand, and 

 from the observations of Krukenberg, Le Dantec, Miss Green- 

 wood, and A. Dixon and myself on the digestive processes 

 and ferments of Protista of animal habit, it appeared probable 

 that in cases where a cell utilises the reserves stored up in 

 its own interior, enzymes would also prove to be present. 



Another consideration had long since been also forced on 

 me by the study of the modes of cellular multiplication. The 

 normal course of the cell is to increase to double its mass, 

 and then to divide at Herbert Spencer's "limit of growth;" 

 yet, how is it that in so many reproductive cells growth 



