METHOD OF CELL DIVISION IN MONIEZIA. 127 



Child in 1904 called attention to the lack of mitoses in the 

 reproductive organs of the cestode Moniezia and asserted that 

 amitosis takes its place. He further elaborated this conception 

 and furnished more data in 1906 and 1907. As the object of 

 this research is either to corroborate or to disprove his conclusions, 

 and as it deals with them at length later, no further attention 

 will be given to his earlier papers in this place. In a later paper 

 ('io) he brings forward no new evidence but merely reiterates 

 his former position. This work consists largely of an attack on 

 my observations on Tcenia ('09). He criticises my paper as 

 presenting evidence of a negative character only; as being upon 

 an entirely different genus and perhaps on different stages from 

 those in which he observed amitosis; as prematurely generalizing 

 from incomplete data; as using preconceived hypotheses; and 

 finally, as being the work of a novice who "is likely to be guided 

 to a greater or less extent by the views of his instructor." I may 

 venture a reply to the main points of this list. I regret to have 

 my paper taken solely as a criticism of Child's work; it recounted 

 the facts as I believe them to exist in Tania; its field, it is true, 

 is limited to the oogenesis and cell multiplication of certain so- 

 matic tissues in this worm, but no attempt is made to apply its 

 conclusions to any of Child's work not upon a similar field (a 

 fact which he does not seem to have appreciated). I found no 

 evidence of amitosis in that field and as Child had covered a 

 similar one it was not only natural but necessary that I should 

 compare my results with his. As to the negative character of 

 my evidence, I would ask whether the failure to find evidence of 

 a certain process, using proper methods and exercising due dili- 

 gence, is not positive evidence of the lack of that process. Of 

 what more would positive evidence consist ? As to my not having 

 studied the proper stages little need be said ; no method of pro- 

 cedure other than beginning at the scolex and working backward 

 ever occurred to me. As to the fact that I studied a different 

 genus, he says, "Such records (referring to the results published 

 in his previous papers) cannot be controverted ... by observa- 

 tion upon another genus and species. . . ." His views upon this 

 point, it seems, have undergone a change. In his "General 

 Conclusions" to "Amitosis in Moniezia" ('04) he said, "It is 



