No. 3.] STUDY OF STENOSTOMA LEUCOPS O. SCHM. 265 



epithelial cells. He also states ('82, p. 259) that the integument 

 of Stenostoma lencops is constructed like that of Microstoma 

 lineare. 



Any well preserved section clearly shows that the circular 

 muscle fibres of the integument of Stenostoma leiicops lie next 

 to the epithelial cells (Fig. 2). 



Karyokinetic figures were observed in the epithelial cells. 

 The axes of the spindles are generally parallel to the surface of 

 the integument (Fig. 2). 



Parenchyme. 



The parenchyme of Stenostoma leiicops occupies all of the 

 body cavity which is not occupied by the alimentary canal, the 

 water vascular and nervous systems, and the sense organs. It 

 completely surrounds and supports these organs, adapting itself 

 to their shape. 



On account of the large alimentary canal, the parenchyme is 

 developed to a very small extent. In the living worm it may be 

 seen in optical section as a light gray, almost transparent mass, 

 surrounding the brain and pharynx, in a narrow strip along the 

 sides of the intestine, and in the triangular area between the 

 posterior end of the intestine and the posterior end of the 

 body. 



When the living worm is examined it may be seen to throw 

 the body wall out into a series of wave-like folds along the intes- 

 tine, thus making a large — in optical section, triangular — 

 space between the integument and the intestine. When this 

 takes place fine, clear, protoplasmic strands may be seen running 

 through this triangular space from the intestine to the integu- 

 ment. It could not be determined in the living worm whether 

 or not these strands unite with one another. There is also to 

 be seen a finely granular fluid mass filling the whole space 

 between the strands. 



At the same time that this space between the intestine and the 

 integument is being formed by the throwing out of the fold of 

 the integument, this finely granular fluid may be seen to flow 

 from the surrounding parenchyme into the space and fill it. 



When a worm whose integument has been ruptured moves 

 through the water under a cover-glass, it leaves behind it a train 



