230 



The above observations on Bermuda Mollusca have to do with 

 species from several classes. There is a- general agreement between 

 these in the presence of vacuoles, and of cytoplasmic bodies which 

 react to Sudan III and to osmic acid in such a way as to indicate 

 that they are of a fatty nature. 



Semiscolex. 



Since the publication of our last article we have made a some- 

 what extended study of the nerve cells of the leech Semiscolex. This 

 animal is very abundant in the waters of Oneida Lake. It adapts 

 itself well to laboratory conditions, and is, in some respects, a form 

 well suited to experimental work. 



In the nerve cells of this form we have found conditions quite 

 similar to those already described in other animals. In the living 

 ganglion cells of well fed animals taken in the early fall are to be 

 seen more or less numerous small bodies, which are apparently 

 solid and almost transparent. In this animal they are very difficult 

 to see on account of their lack of color, but after a little practice 

 one can make them out. In sectioned material which has been stained 

 with thionin, they are to be seen with great clearness. They lie in 

 a zone immediately beneath the cell membrane, and also may be 

 found to extend well in toward the nucleus. In none of the cells which 

 we have recently examined were these deeply stained bodies so numer- 

 ous as in some of the other animals we have examined. 



In close association with these small bodies are also found many 

 vacuoles of various sizes. These can easily be made out within the 

 living nerve cell, but show more clearly in the sectioned and stained 

 material. When first seen in the sectioned material they were thought 

 to be due to faulty fixation, as they were even larger and more numer- 

 ous than our observations upon the living cells had led us to expect. 

 Later observations, both upon the living cells and upon such as has 

 been fixed and sectioned, leave no doubt as to the reliability of our 

 conclusions. They are structures normally present in living cells and 

 are not due to any fault in preparation. 



Our experiments upon the nerve cells of this leech are chiefly 

 along the line of starvation. The animals live well in the laboratory 

 provided that plenty of fresh water is supplied. They may be kept 

 alive without feeding for long periods, and during the term of starv- 

 ation will be seen gradually to shrink in size and to become less 

 active. When the nerve cells from one of these starved individuals 

 are examined, either in the living condition, or as fixed, sectioned 



