STRUCTURE OF CLINOSTOMUM 



209 



to distinguish the different vessels and their connections. In such 

 a preparation the collecting vessel as well as the smaller vessels 

 which are derived from it are readily seen. The appearance of 

 this system of vessels is shown in a free hand drawing (text fig. 1, 

 for which I am indebted to Mr. Fans Silvermale) made from 

 an unusually young live bass worm under slight compression. 

 The collecting vessel can be followed, its size diminishing as it 

 advances until it is lost in the network of its subdivisions. The 

 network shows a predominance of transverse vessels, though 



Fig. 1 Free hand drawing from a young, living, slightly compressed bass worm. 

 Zeiss 2 A. 



with many communicating vessels connecting them, and some 

 which cross over to the other side of the body and become con- 

 tinuous with those of that side. In this preparation the recur- 

 rent vessel could not be seen, but as I shall point out later it 

 seems most likely that it is present and joins the collecting vessel 

 in this part of the animal. 



In the posterior part of the bodj^ these vessels may be somewhat 

 more definitely subdivided into two sorts according to their des- 

 tination, a superficial system which runs to the surface and be- 

 comes the subcuticular vessels and a deep system which passes 



