204 WINTERTON C. CURTIS. 



all, distinguishable from the one proceeding from the first seg- 

 mentation. The specimen represented by Fig. 19, PI. VI., is an 

 exception to the above course of development, in that it shows 

 all the characteristics of a specimen having the non-segmented 

 zone of the early proglottid formation and at the same time an 

 elongated neck. A possible explanation of this as a specimen 

 undergoing regeneration after mutilation is given on p. 215 of this 

 paper. 



A discussion of the bearing these facts have upon our views 

 regarding the nature of the cestode body in given on p. 217. 



II. DISCUSSION OF THE LITERATURE. 



In my examination of the literature I have relied upon Braun's 

 monograph (Bronn's Thierreich) as a trustworthy summary of the 

 facts established regarding the Cestoda down to about 1896, 

 when the parts of this volume referring to the points in question 

 appeared. Upon the particular subject of the method of pro- 

 glottid formation the statements of this author are explicit in 

 several instances and agree with the account which has long been 

 current in our text-books. For example, in the introductory 

 section on Cestoda (p. I 167), he says : " besitzen dem nach die 

 Cestoden Zweierlei Theile : Scolex and Proglottiden : letzterer 

 sind in einer Reihe dem Alter nacht geordnet, so das die jiing- 

 sten dem scolex am nachsten, die altesten von diesem am weites- 

 ten entfernt sind." On p. 1224, under the paragraph entitled 

 " Intercalation und Verwachsung von Proglottiden," Braun says : 

 " wir haben alien Grand zu der Annahme dass die Proglottiden 

 die ein Bandwurm besitzt oder jemals besessen hat, alle nach 

 einander und zwar in der durch die Stellung gegebenen Reichen- 

 folge am Scolex sich gibildet haben, dass also niemals durch ein- 

 schalten neuer Proglottiden die Zahl der Gliedei' an einem Band- 

 wurme vermehrt wird. ' Again, under the section of the 

 Embryology entitled " Die Uebertragung der Finnen in den 

 Endwirth," etc. (p. 1592 on), he refers in a number of places to 

 the appearance of the segments, but makes only indirect mention 

 of the order in which they appear, the evident reason for this 

 being that there is only one method of proglottid formation 

 known. 



