184 



DR. F. E. BEDDARD ON THE 



one orifice to the exterior, the dorsal. His statements in the 

 text as to the double opening seem plain enough. I confirm 

 these statements as to the presence of both a dorsal and ventral 

 orifice of the vertical tube. Moreover, I may point out that 

 there is no histological difference between the two. In both 

 cases the actual orifice is small and guarded by an involution of 

 the outer cellular layer of the body ; it is obviously formed in 

 fact by an involution from the exterior. The identity of struc- 

 ture shown by the two openings is a further proof of the truth of 



Text-figure 5. 



t. 



£ $MV* 



d: 



Pi 

 1 / 



A 



Part of a horizontal section through a proglottid of Amabilia. 



a. Dorso- ventral tube of water-vascular system, d. & v. Dorsal and ventral trans- 

 verse vessels, o. Ovary, t. Testes (forming in this particular proglottid a 

 continuous hand unbroken in the middle line). 



the view that this tube is a part of the water- vascular system, 

 and that its connection with the generative system is entirely 

 secondary. It has, in fact, nothing to do with either a uterus 

 or a vagina. Cohn has directed attention to the probability that 

 this point of view is also supported by the fact that the vertical 

 tube is fully developed in anterior segments where the generative 

 system is either invisible, or if visible to be seen only in its 

 earliest rudiments, as well as by the general structure of the walls 



