The Histogenesis of Cj'sticercus pisiformis. 207 



an ihren definitiven Platz hinwachsen." This theory of Blochmann's 

 has been supported by Pint^s^er (1896, p. 8). However, he has 

 adduced no developmental facts in support of this hypothesis; his 

 argument being-, on the contrary, a purely theoretical one. Recently 

 BuGGE has endeavored to present evidence in support of this Bloch- 

 mannian hypothesis. This author has studied and figured many 

 developing fiame cells in Taenia crasskollis, Moniesia expansa, Ligula 

 simplicissima , Cysticercus fasciolaris, tenuicollis and 

 Coenurus cerebral is. Thus he has studied their development 

 both in larval and adult Cestodes. A brief summary of his obser- 

 vations on the development of the flame cells in Cestodes follows. 

 The walls of the excretory ducts are lined by epithelial or wall cells. 

 One of these cells moves into the parenchyma away from the wall 

 of the duct, maintaining, however, its connection with the wall thru 

 a gradually lengthening protoplasmic strand (Figs. 1 and 2). Two \) 

 or four "nucleoli" now appear in the nucleus -) (Figs. 10, 11 and 13). 

 Meantime, the cell is increasing in size and the nucleus has divided 

 into four parts (Fig. 14), while simultaneously the cell is moving 

 further from the duct and its connection therewith is becoming- 

 thinner and longer. The lower of the daughter nuclei now separates 

 from the three upper and with the protoplasm surrounding it remains 

 behind, that is, nearer the duct than the other three nuclei. These 

 latter with their surrounding cytoplasm are the "three upper cells" 

 of this author, while the former is his "fourth cell". At the bases 

 of the "three upper cells" there now appear the rudiments of the 

 basal plate and ciliate process (Fig. 17), while from the "fourth cell" 

 are formed not onlj' the funnels of the three fiame cells, but also 

 the capillary connecting these with the duct (Figs. 21, 22 and 23). 

 The essential point in his demonstration is the occurence of the 

 several developmental stages successively further and further awaj' 

 from the duct. If now, we find the fully developed flame cells close 

 to the duct and the younger stages far removed therefrom, it would 

 seem that the argument for such a migration and transformation 

 of the "wall cells" into flame cells will not stand. And this is 

 precisely what I have found in several cases, in which I have seen 

 evidently young stages with cells not j^et separated, lying close to 



1) Where only two are shown they presumably divide later to 

 form four. 



2) Bugge's distinction here between cell body and nucleus is 

 not clear. 



