62 i.ARY N. CAI.K1.V-. 



scendants give rise to abnormalities. . . . Those which lose 

 the posterior part only, always multiply normally by fission. . . . 



A sort of paralysis attacks cells thus injured in their nuclei" 



('92- P- 78). 



The number of monsters (four) obtained by Balbiani is too 

 -mall to support such a generalization. My experiments, in 

 which live of the thirteen monsters were derived from cells cut 

 in the posterior half throw this suggestion out of further con- 

 sideration. 



A more modern view of the nature of physiological processes 

 of the cell was suggested by R. Hertwig ('03) and has been 

 elaborated by himself and his school in numerous publications. 

 This theory according to Popoff's ('08) presentation, involves the 

 view that the quotient obtained by dividing the cytoplasmic 

 mass by the nuclear mass is fairly constant under "normal" 

 conditions, and just as long as this relation varies only within 

 narrow limits, the cell functions are normal. But if by dis- 

 proportionate growth of either cytoplasm or nucleus, the nucleus- 

 protoplasm relation is changed to favor either one, then the cell 

 gets into an "abnormal" condition. In order to become "nor- 

 mal" again, the "normal" nucleus-protoplasm relation must be 

 reestablished. Cell division, Hertwig believes, is the means 

 whereby normal relations are reestablished. He postulates, 

 furthermore, two periods in the growth of the nucleus; one 

 "functional." the other "divisional," the former beginning shortly 

 alter division of the cell and lasting until shortly before the 

 following division, the nucleus growing less rapidly than the 

 cytoplasm and disturbing the nucleus-protoplasm relation in 

 fax or of the cytoplasm. This disturbance of "normal" relations 

 persists up to a certain point which Hertwig calls the nucleus- 

 protoplasm -tension -moment i Kernplasmaspannungsmoment), 

 u In'di In- Hoards as the immediate inciting cause of cell division, 

 tin- first effect being the rapid "division growth" ot the nuclei!-. 

 The result of the division 1 1 HI- started is a return to the " normal " 



A 



nucleus-protoplasm relation. 



The use ol terms normal and abnormal in this connection i- 

 hardlx appropriate, for cell division is certainly a normal process 

 and .ill Stages leading to it must likewise be normal, hence an 



