INTRODUCTION. li 



forming polypide seems to me to be enveloped in the endo- 



sarcal plexus, and to be (in all probability) 



produced by it. In PediceUina the origin 



of the polypide is doubtful *. So the 



matter rests for the present. In a large 



number of cases undoubtedly the poly- 2 



pide owes its origin not to the endocyst 



proper, but to the tissue composed of 



fusiform elements, which has its most 



familiar representative in the funiculus. 



It may be, as Joliet suggests, that the ^""'"'^ Zoc^cium 



•' ' aa } f>/ Beania.— ^. Zooe- 



authors who have referred it to the en- cium. hd. Polypide- 



docyst have not been sufficiently alive to " 



the distinction between these two tissues ; it may be that 



the function is to some extent shared by the endocyst. 



Further investigation, along the lines now indicated, must 



decide the point. 



The question arises, whether this tissue, constituted as 

 we have seen, and endowed with such physiological attri- 

 butes, is to be regarded as a mere dependence of the 

 endocyst, or whether it is more properly characterized as 

 one of the principal elements of the Polyzoan structure. 



Looking to the peculiarity of its histological character, 

 to the undoubted importance of the part which it plays in 

 the animal economy, and to its distinctness and definite- 

 ness, as awJiole, Joliet is amply justified, in my judgment, 

 in distinguishing it by a separate name, and assigning it a 

 special rank. He is also wise, at the present stage of 

 inquiry, in selecting a name for it which has no theoretic 

 flavour, but simply indicates a fact. 



* Salensky, " Entoproctes," Ann. Sc. Nat. ser. 6, vol. v. 



e2 



