64 <.ARY N. CALKINS. 



"normal" condition- ot the divi-ion energy might have been 

 reestablished. 



In reference to my Paramccinm work of 1904 Popoff states that 

 at tin- final period of depression the nucleus-protoplasm relation 

 was changed to the ad\ .image of the nucleus and he argues that 

 this condition may have been the cause of the depression (he. cit., 

 p. ,VV)|- As my paper of 1904 makes no reference to the 

 nucleus-protoplasmic relation he drew his conclusion from the 

 photographs of the cells at the end period of depression, but nat- 

 urally, he did not realize that when the cells thus photographed 

 were killed, they had lived for days without dividing. Under 

 -uch conditions, like any other Paramccinm cell under similar 

 conditions, they were "abnormal" so far as the nucleus-proto- 

 plasm relation is concerned. ' 



In the latter part of the first section of Popoff 's paper of 1908 

 he gives an inkling of a possible interpretation of the nucleus- 

 protoplasm relation in the statement: "Die Kernplasmarelation 

 wird ein morphologischer fassbarer Ausbruck der jeweiligen 

 Chemismus der Zelle bleiben." With this interpretation we are 

 inclined to agree, and we look upon the changeable nucleus- 

 protoplasm relation as an unstable effect produced by varying 

 conditions of nutrition, temperature, or vitality and not at all 

 as a cause of division or depression or of vitality. In a mutilated 

 Paramecium the nucleus divides equally, the cell unequally; the 

 smaller fragment has a full size nucleus and a much deranged 

 "nucleus-protoplasm" relation; yet, in some cases at least, it 

 behaves like a normal cell, dividing at the proper time and again 

 forming dissimilar products, one of which is perfectly normal, 

 the other again abnormal (expt. 25, p. 57). 



By removing a portion of a cell there can be little doubt that the 

 ordinary chemical interchange, or perhaps the physical or 

 electrical potential, of cell and nucleus is violently disturbed. 

 In forms with a labile protoplasm, as manife-tcd in some fonii- 

 of Paramccinm and as in Stentor, Loxophyllum Spathidium, etc., 

 the wounded cell regenerates quickly, but in other races of 

 Pnninn-i inm and in non-nucleated fragments of other protozoa, 

 ihe more -table protoplasm does not respond and regeneration 

 fail-. l)ivi-ion of the fragment indicate- that the power of 



