420 



PROCEEDINGS OF THE ACADEMY OF 



[July, 



Secoxdarv Table. . 

 For description see page 419. 



Table 



I. 



II. 



III. 



IV. 



V. 



VI. 



VII. 



VIII. 



IX. 



X. 



XI. 

 XII. 



XIII. 



XIV. 



XV. 



XVI. 



XVII. 



XVIII. 



XIX. 



XX. 



Elodea 2 exp. 



Mjaiopliyllum 6 " 



Sediment 13 " 



Fgeces 2 " 



Flat dish 2 " 



1 " 



Air bubbles 5 " 



(See Special Table,p.431) 

 Excretions cone. . . 1^ " 

 " dilute . . 5 " 



(See Special Table.) 



Numbers " 



Shell salts (see Special 



Table). 

 Temperature (see Special 



Table, p. 419). 



Cold exp. 



Dark " 



Large area 2 " 



Large volume 8 " 



Alternate heat and 



cold 4 " 



Alternate light and 



dark " 



Alternate starving 



and feeding " 



Absence of 4 exp. 



" 4 



" 4 



" 



i Jar and slides 2 



Battery jar 



Absence of 2 



Warm 11 



Light 5 



Small area 8 



Small volume ... 



Warm 

 Light . 



Inde- 

 terminate. 



4 exp 



7 

 5 

 1 

 4 

 6 



With food. 



V. Experiments. 



1. Effect of Food. — Various authors (Semper, Ullyet,^ Cockerall,^ 

 Walter, etc.) have shown that Lymncea will eat animal as well as vege- 

 table food. However, the latter furnishes the normal diet. This con- 

 sists of diatomes, desmids, unicellular and filamentous algse, the leaves 

 of water plants, and dead leaves of trees. If a snail after hatching is 

 placed in a clean battery jar with 500 cc. of clear pond water that 

 snail will grow, the necessary amount of food being supplied by the 

 microscopic algae introduced with the water which will increase faster 

 than the snail can eat up. If the temperature is favorable, in the course 

 of two months the snail will reach 7 mm. or 8 mm. in altitude and 

 become sexually mature. The fact that the supply of food keeps 

 ahead of the demand is interesting and led to a series of experiments 



Boiled water from a jar in which a snail had been raised. 

 Cited from Walter ('06). 



