426 ROBERT W. HEGNER 



Cestoda. Child concluded ('04) from a study of the cestode 

 Moniezia expansa that the amitotic method of cell division occurs 

 in the antecedents of both the eggs and the spermatozoa. This 

 writer has published a series of papers upon this subject using 

 Moniezia expansa and M. planissima for his material ('04, '06, 

 '07, '10), and his principal conclusion is that in these species the 

 division of the cells destined to become eggs and spermatozoa 

 is predominantly amitotic. Mitotic division also occurs but 

 comparatively rarely. Cells which have divided amitotically 

 then divide mitotically during maturation and form typical ova. 



The nature of the nuclear division in the cestodes was later 



investigated by Richards ('09, '11) who studied the female sex 



organs of the same species employed by Child as well as- material 



obtained from Taenia serrata. Richards finds that mitosis 



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unquestionably occurs in the young germ cells but was unable 

 to demonstrate amitosis. Richards claims that amitosis cannot 

 be demonstrated except by the observation of the process in the 

 living material and the subsequent study of this material by 

 cytological methods.- Child ('11) agrees with Richards that 

 amitosis cannot be demonstrated in fixed material but never- 

 theless concludes after an examination of Richard's preparations 

 ''that direct division plays an important part in the developmental 

 cycle of Moniezia, in the germ cells "as well as in the soma" 

 (Child, '11, p. 295). 



Finally Harman ('13) was unable to find any evidence of amito- 

 tic divisions in the sex cells of either Taenia teniaeformis or 

 Moniezia and concludes that the conditions which suggest ami- 

 tosis can just as well or better be explained by mitosis. Experi- 

 ments with living cells of Taenia were without results, since the 

 cells did not divide when placed in Ringer's solution, although 

 they continued to live outside the body of the host for forty- 

 eight hours. Morse ('11) likewise failed to observe divisions in 

 living cells of Calliobothrium and Crossobothrium which were 

 kept in the plasma of the host. 



Insecta. In the Hemiptera amitosis was described by Preusse 

 ('95) in the ovarian cells of Nepa cinerea and similar conditions 

 were reported by Gross ('01) in insects of the same order. Gross, 



