CELL MULTIPLICATION IN THE SUB-CUTICULA OF 



DILEPIS SCOLECINA. 1 



DALTON G. PAXMAN. 



INTRODUCTION. 



The process of cell division in cestodes as compared with that 

 in other Metazoa is apparently quite abnormal. An examination 

 of cestode material at once reveals the fact that mitotic figures 

 are very rare, and that an explanation of the process of cell 

 division analogous to any of the common types is apparently 

 impossible. The opinion of the various workers in cestode cy- 

 tology, as to how cell division is taking place, varies greatly. 

 Some state that it occurs by mitosis, others by amitosis, while 

 it has been asserted that nuclei arise ' de novo ' from the cytoplasm. 



Child ('07) noted the apparent infrequency or total absence 

 of any evidence of mitosis in Moniezia, even in regions where 

 rapid growth was taking place. He says, "If my observations 

 are correct, amitosis is the more common method of division in 

 the generative cycle, except during the period of maturation and 

 early cleavage. And in the somatic cells of the adult body it 

 appears to be the usual method at all times." 



Young ('08), working with Cysticercus pisiformis describes 

 what he calls the "de novo" formation of cells. He observed 

 irregular masses of coarsely granular cytoplasm lying in the 

 meshes of the parenchyma network. These masses contain 

 numerous small deep staining granules scattered haphazard 

 through the mass. Shortly succeeding the formation of these 

 granules, a nuclear membrane is formed around them; the 

 newly formed nucleus, together with a small mass of cytoplasm, 

 becomes partly constricted from the parent mass; and the 

 daughter cell has been formed." 



Further, he says: "I believe that the nucleus in these forms 

 is not a morphological, but a physiological entity; that the 



1 A thesis presented to the graduate faculty of the University of North Dakota 

 in partial fulfilment of the requirements for a master's degree. 



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