STUDIES ON BIOLOGY OF FRESHWATER MUSSELS. 23! 



the checks was 1.2 C. At the beginning the checks averaged 

 12.6 higher than the others, and at the end averaged 14.1 higher. 

 Nearly ten degrees (9.6) separated the lowest check from the 

 highest temperature in an experimental jar. As was to be ex- 

 pected the atmospheric temperatures created considerable varia- 

 tion in the checks (6.4) and much less in the cooled jars 

 (2.4 C.) 



Of the twenty animals used only ten showed partially renewed 

 styles. Of these ten only two occurred at the reduced tempera- 

 ture, and eight in the checks. The two which appeared in the 

 low temperature were smaller than any of the eight formed in the 

 checks. Moreover, the two were both in Anodonta, and Ano- 

 donta has shown a greater response always than Lain[>silis, never 

 failing to show some renewal. Lampsilis more slowly loses and 

 more slowly regains its style than Anodonta. 



While the number used is small, exact quantitative results are 

 here unnecessary, and there is sufficient demonstration of the 

 qualitative effect of temperature upon style formation. This 

 effect may be partially explainable through the effect of tempera- 

 ture upon the cilia and the rate of ingestion. But the reason men- 

 tioned above is probably more pertinent, for the intestine was 

 usually found to contain food in the experimental animals. 



So long as the quality of the ingested material is right, the 

 quantity required to initiate the formation of the style is very 

 small. At times a single battery jar of water dipped at random 

 from the surface of the littoral has contained sufficient food to 

 restore it, in part. Held to the light the water had given no hint 

 of green. But after it had been siphoned from one to two hours, 

 the resulting thread-like crystalline style contained a conspicuous 

 core of green. 



Where food is abundant the length of time needed to renew 

 secretion after the beginning of feeding is very short. A fair 

 beginning may sometimes be observed within fifteen to thirty 

 minutes. Large well-formed styles are sometimes secreted in 

 four hours or less. The time depends largely upon the degree of 

 .starvation. More often twenty-four hours, at least, are required. 

 On the whole it is a much more deliberate process than in some 



