72 journal of Comparative Neurology and Psychology. 



of such stimulation it was found that, unhke the granules found 

 in Limax, these bodies are extremely resistant and would not change 

 in appearance during the time which the cells would live under 

 these unusual conditions. This fact, as well as their different 

 appearance in the cell, indicates that they are of a different nature 

 from those in Limax. They are, however, a storage product and 

 have to do with the nourishment of the cells during times when 

 proper food is unavailable. 



Nature of the bodies. — Many experiments have been made to 

 determine the chemical nature of the golden brown bodies, and 

 while we cannot say definitely just what the substance is we are 

 in a position to state to which general class of substances it belongs. 

 It is even possible that the bodies are not of constant composition. 

 Most of the tests used require a long time for their action, and in 

 some cases even failed to act at all. Osmic acid blackens the 

 bodies after a long time. In many of the specimens the blacken- 

 ing was merely superficial, indicating that the substance is a highly 

 resistant or that it is not a fat but some substance which may break 

 up into a fat and some other substance. The tests w^ith Sudan 

 III and with cyanin indicate the same thing. With Sudan III 

 the bodies assume an orange color for a short time. The color 

 soon disappears, however, and leaves the body a sort of yellow 

 lemon color. With cyanin the action is slow. The bodies stain 

 a deep blue, which is sometimes temporary and sometimes more 

 lasting. In ether the bodies swell up and clump together, becom- 

 ing gradually dissolved and diffused throughout the cell. The 

 resistance of the granules is shown by the fact that it requires 

 frequently an hour or more to dissolve a granule i /< in diameter. 



On account of the difficulty in making these tests it was thought 

 for a time that they might be proteid in character, but all attempts 

 to digest them with pepsin have so far failed. The results of the 

 tests seem to indicate that they are some sort of a fat. 



Further tests with concentrated sulphuric acid indicate that the 

 pigment is one of the lipochrome group, the bodies assuming a 

 bright blue color as soon as the acid touches them. 



Venus. — Our experiments upon the nerve cells of the edible 

 clam, Venus, have been few in number and serve only to add 

 emphasis to what has already been stated. We find in the nerve 

 cells certain yellow spots, whether solid or semifluid in character 

 we are at present uncertain. The color is not the same as that of 



