126 Victor E. Emmel. 
changes in cytoplasm and nucleus. It remains for further observa- 
tion to answer the interesting question whether the parallel occur- 
rence of these structural changes is due to the existence of a signifi- 
cant correlation between the nucleus and the cytoplasm in the regen- 
erative activities of the cell. Such a correlation is supported, for 
example, by Eyeleshymer’s (04) thorough work on the muscle cell of 
Necturus, in which that investigator finds strong evidence that the 
nuclear material plays a most important role in cytoplasmic syn- 
thesis. He suggests that “cellular degeneration and regeneration are 
accompanied by volumetric, structural and chemical changes in 
chromatin” (p. 307). 
5. Cell Division.—Reference has already been made to the fact 
that mitotie cell division was not observed until the second day follow- 
ing the operation, and then only in the epidermal cells. Thirty- 
eight hours after the amputation, two mitotic figures were found in 
serial sections of the right chela and four figures in the left chela of 
the same specimen. Twelve hours later, eighteen mitotic figures 
were counted. Preceding mitosis the nucleus migrates toward the 
outer surface of the epidermis so that the mitotic figures are always 
found near the periphery of the epithelium. Regarding the ques- 
tion of amitosis in the early stages of regeneration, it may be said 
that there was no evidence found for direct or amitotie division of 
the epidermal cells during the thirty-eight hours preceding the first 
mitosis. Each migrating nucleus seems to maintain its original 
unity up to the time at which mitosis first occurs. 
Without entering further into a discussion of this interesting ques- 
tion of amitosis, attention may be called to the contrast of the present 
results as compared with ohservations on the compound crustacean eye, 
where it appears that in “all cases of the regeneration of the eye the 
nuclei are increased by amitotic division” (Steele, ’08, p. 183). 
Steele, referring to Reed’s (704) conclusion that mitotic figures do not 
occur in the early stages of the regenerating limb of the crayfish, sug- 
gests (p. 184) that amitotie division may possibly have taken place 
“during the preparatory stages at least.” In regard to this question, 
the evidence, in the lobster at least, is of a negative character. It ap- 
pears rather that an increase in both the quantity of cytoplasm and 
