AN EVENING WITH THE AQUARIUM 



AND SNAILERY 



One evening, shortly after our trip to the woods, we met by appoint- 

 ment at Professor Parker's home for the purpose of spending a few 

 hours in study. The Professor greeted us in his usual hearty manner, 

 and we were soon deeply engrossed in our favorite subject. 



Of great attraction to us was a large rectangular aquarium (about 

 two feet in length and one foot in width and depth), which was tenanted 

 by various species of pond snails, and fresh-water clams. A light was 



placed behind the tank, and thus we were 

 able to study the habits of the imprisoned 

 animals. A clam was slowly pulling its shell 

 through the muddy bottom, its siphons ex- 

 tended, and the little cilia moving nervously 



Fresh-water limpet Ancylus -n .c -n i 11 i xi 



rivularis, as seen through the about, Proiessor rarker told us to watch these 

 magniflei! aquadum> Greatly siphons closely. A stream of water was con- 

 stantly passing clown the lower siphon, a fact 



of which we became aware by seeing several very small particles 

 of vegetable matter float near the siphon and quickly disappear into 

 its orifice. The upper siphon was violently expelling waste matter, 

 and we could see the little particles thrown out into the water. We 

 noticed that this siphon seemed to move like clock work, opening and 

 closing at regular intervals, each time ejecting a current of water filled 

 with waste matter. Out of curiosity we counted these pulsations and 

 recorded twelve each minute. 



In another part of the aquarium, a number of pond snails were 

 gliding slowly along. On one side, several large snails were eating 

 the growth of green vegetable matter which had accumulated. This 

 side presented a curious appearance, for each snail hud left a clear 

 path behind it where the scum had been cleaned off. "We could 

 plainly see the mouth open and close as the animal grazed along. 

 Every time the mouth opened, the tongue was thrust out, and the 

 whole operation reminded us of a cat lapping milk. The brown jaw 

 was also plainly seen. 



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