OCCURRENCE OF AMITOSIS IN MONIEZIA. Ill 



of any value at all as a means of discovering the visible phenom- 

 ena of cell division, I can only conclude that direct division occurs 

 in Moniezia as I have stated and that it can be seen readily 

 enough by anyone who is willing to take sufficient care in 

 preparation and observation. 



Moreover, I have not, so far as I am aware, attempted at any 

 time to " balance " my observations against those of others. 

 The real point at issue is not my observations against those of 

 others, but my observations against a hypothesis, which cannot 

 be proved by observation, viz., the chromosome hypothesis, for 

 the only real objection to the acceptance of my observations at 

 their face value is the existence of this hypothesis. I do not 

 wish to enter into fruitless discussion of the hypothesis, but 

 merely to emphasize the fact that I have attempted in every way 

 possible to make the record of my observations a record of actual 

 fact. Such records cannot be controverted either by observations 

 on another genus and species or by invoking a hypothesis which 

 is far from being proved. It is interesting to note that Richards' 

 paper is to a considerable extent devoted to " balancing " his 

 observations against my own, although both according to him 

 are made on the " unfavorable " cestode material. 



Turning now to certain matters of detail, we may consider first 

 certain points with respect to the parenchyma. My observations 

 on amitosis began with a study of the neck-region, i. e., the 

 region between the scolex and the first visible proglottids. In 

 this region the tissue of the body consists mainly of parenchymal 

 cells, muscle fibers, the nerve cords and the nephridial canals. 

 At the posterior end of this region the proglottids become visibly 

 marked off one after the other, each including a certain portion 

 of the tissue. In other words, the cells which constitute each 

 proglottid either preexist, or arise by the division of preexisting 

 cells in the neck-region, or else they must arise de novo. Ex- 

 amination of transverse sections at short intervals from the scolex 

 backward into the proglottid region shows a very considerable 

 increase in the number of nuclei, as I have determined by actual 

 counts of the nuclei in the sections. In short there can be no 

 doubt that new parenchymal nuclei are formed in this region, and 

 when we consider the enormous number of proglottids formed 



