(106) 

 sectiori is stained deeply with iron haematoxylin and eosin, it 

 will show plainly that there is no cavity in the cord but that 

 it is made up o^ a mass of fibers surrounded by a nucleated 

 sheath. Caldwell (5) considers the structure to be a hollow 

 nerve cord; Eenham (2) says that it has a semi-fluid contents and 

 chat he has been unable to make out any punctated nerve substance: 

 and Cori (4) states that it is an axis cylinder. 



1 have endeavored to find some coiinection between ti~.e cord 

 and the ganjrlion but have liOt been very successful. In the re- 

 gion 0-^ ti.e ganglion: i. e, , between the mouth and the anus, the 

 sheath o -^ the nervo cord does not seem to differ in thiclaioss or 

 character from the same structr,re in other parts. The cells of 



th.e ganglion, however, sena out processes wiiicli in sections are 



the 

 frequently seen applied to^ sheath but 1 6'ould make out no connec- 

 tion between the fibers of t.i ^ n-rve ring and those of the cord. 



Kowalevsky (11), Cori (4) and Torrey (2ii) have all found 

 the nerve ganglion, while Renhain (2) aonies its existence in P. 

 Australis. It undoubtedly exists in P. architecta, is situated 

 at the base o^ the anal papilla between the anus ana the inouth, 

 aJTid lies above the nerve cord between the anal papilla and the 

 nerve rinj:^. ("Pig, 64) 



The ganglion consists of nerve fibers aiid nerve cells ana 

 the latter have at leo.st two processes. m.ila ^ is a defmiit 



