208 Robert Thompson Young, 



the sub-cuticula, or midway between it and the ducts; while in 

 other cases I have found fully developed flame cells close to the 

 ducts. While these may be exceptions to the general rule, certainly 

 in connection with my observations on the developing- flames in young 

 Cysticerci, they cast grave doubt on this Blochmann-Bfgge-Pintnee 

 theo]y of the epithelial origin of the flame cell. 



But can Bugge's observations, as to the accuracy of which there 

 seems no opportunity for question, be explained on any other grounds 

 than those upon which he explains them? There is nothing to 

 prevent their interpretation on the basis of a flame cell development 

 from modified parenchyma cells in situ, as it occurs in 

 Cysticercus pisiformis. But why should these developing 

 cells be found so numerously around the excretory ducts if they are 

 not derived from the "wall cells" of the latter? In my own pre- 

 parations the ducts are not usually surrounded by these 

 developing cells, and where groups of them are found near the 

 ducts it is apparentlj^ in a region of active cytogenesis, for the 

 cells of the parenchyma are very numerous there also. 



In any event, in the earlier stages of Cysticercus I am prepared 

 to deny absolutely the epithelial origin ot the flame cells, for 

 here I find the flame cells developing prior to the appearance of 

 the ducts, but how could this be possible if they originated from 

 the walls of the latter? 



As many as four developing flame cells may occur in a group 

 as shown in Fig. 40. ^) 



I question the origin ascribed by Bugge to the "fourth cell" 

 which I prefer to call the "capillary cell". Numerous groups of 

 developing flame cells have been observed without the discovery 

 in any instance of a common origin for the flame cells and the 

 capillary cell. Fig. 39 represents a possible exception to this state- 

 ment. There is no positive evidence, however, to show whether the 

 capillary cell, ce, originated in a common cell with the two flame cells, /", 

 or whether it has originated independently. Further, in the group of 

 three developing flame cells represented in Fig. 42 (the lower 

 cell is cut in section, the other cells are seen in side view), there 

 is positive evidence of the absence of any capillary cell. There is 

 a slight thickening of the capillary wall at d, but no evidence of a 

 nucleus anywhere along its course. 



1) Four is the largest number observed in one group. 



