STRUCTURE OF CLINOSTOMUM 205 



information as to their physiological significance. It is possible 

 that they are merely mucin-forming organs and that they acquire 

 a temporary connection with the oesophagus. 



The intestine. The intestine consists of a part crossing the body 

 transversely (fig. A: A) which, after bending, continues as the two 

 long lateral caeca. The caeca lie in the center of each half of 

 the bod}^ and extend (fig. 2) to the level of the excretory bladder. 

 The walls of the caeca are not entire; blind pouches extend out- 

 ward from them. These pouches are not as large and distinct in 

 the material after fixation as they are in life. Fig. 13 a is a free- 

 hand drawing of the living organ in a specimen just liberated from 

 a bass cyst. The pouches arise on both sides of the intestine; 

 they are very numerous and close together and are not long and 

 slender. The form of these pouches distinguishes C. marginatum 

 from C. heterostomum. In the latter (Braun, '00, fig. 1) there 

 are a few very long and slender diverticula which are confined to 

 the outer side of the intestine. In the presence of these intestinal 

 pouches Clinostomum resembles Fasciola hepatica and the pla- 

 narians. Fig, 15 is a camera drawing of the wall of the intestine. 

 The pouches are conspicuous in some places and absent in others. 

 This corresponds with the facts seen in life ; in bass specimens the 

 pouches are contractile and at moments are drawn back into the 

 wall. The wall itself is contractile; in life its movements are very 

 conspicuous. The lumen is filled with a fine grained material 

 lemon yellow in color. This flows back and forward, streaming, 

 the pouches empty themselves of it or fill with it and the contrac- 

 tions of the wall may obliterate the intestine entirely for a 

 moment. 



The structure of the intestine wall from a fully matured heron 

 worm is shown in fig. 13. The epithelium presents two distinct 

 zones, a deeper basal one and, arising from it, a second zone of 

 separate columnar structures. The basal zone is a continuous 

 protoplasmic layer, in which distinct nuclei occur at somewhat 

 regular intervals, but without any walls dividing it into cells. 

 This basal syncytium takes the stain readily. The processes of 

 the outer zone show a relation to the nuclei below though they 

 are not always strictly over them. In a section, (fig. 13 on the 



JOUENAL OF MORPHOLOGY, VOL. 23, NO. 2 



