GERM CELLS IN THE ARTHROPODA 137 



evidence of amitotic divisions in the sex cells of either 

 Tcenia tenioBformis or Moniezia and concludes that 

 the conditions that suggest amitosis can just as well 

 or better be explained by mitosis. Experiments 

 with living cells of Tcenia 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 

 (1911) likewise failed to observe divisions in living 

 cells of Calliobothrium and Crossobothrium which 

 were kept in the plasma of the host. That the 

 observation of amitosis in living cells is possible 

 seems certain since Holmes (1913) has recorded an 

 actual increase in the number of epithelial cells 

 from the embryos and young tadpoles of several 

 Amphibia that were cultivated in lymph, and has 

 noted various stages of amitotic nuclear division, 

 although no convincing evidence was obtained that 

 this was followed by cell division. 



Insecta. In the Hemiptera amitosis was de- 

 scribed by Preusse (1895) in the ovarian cells of 

 Nepa cinerea and similar conditions were reported 

 by Gross (1901) in insects of the same order. Gross, 

 however, claims that the cells which divide amitoti- 

 cally do not produce ova but are degenerating or 

 secretory. 



Foot and Strobell (1911) described in ovaries of 

 the bug, Protenor, the amitotic division of certain 

 cells which later produce ova. There is, however, 

 considerable difference of opinion among investi- 

 gators as to the origin of the ova from the various 



