OF ARTS AND SCIENCES. 39 



been connected with the pond by four, eight-inch water-mains, 

 laid side by side at a level with the bottom. It was thought 

 that caddis-fly larvae and dragon-fly nymphs might have found 

 their way through these pipes, and the first observation was ac- 

 cordingly made at the point in the pond where the water-mains. 

 discharge a small stream from the marsh. A hole two feet 

 square was cut in the ice, which was found to be five and one- 

 half inches thick. The water was three feet deep, and at a 

 depth of two feet its temperature was 34 degrees Fahrenheit. 

 The temperature of the atmosphere was 16 degrees at 11 

 o'clock A. M. 



The dredging was done with a sieve net, similar to that fig- 

 ured and described in part O of the U. S. Nat. Mus. Bui. 39, 

 p. 4, and used with such success by Professor Needham in his 

 Adirondack investigations. There was no mud, the excava- 

 tion having been made down to the original solid bottom of the 

 pond. The dredge brought up large quantities of oak and ma- 

 ple leaves which the wind had blown into the water. Many of 

 these bore the familiar markings of the leaf miners, and excres- 

 cences caused by various gall insects, but there was no trace of 

 aquatic life to be found upon them. Bj^ thrusting the dredge 

 under the ice, it was made to explore an area of fully sixteen 

 square feet, but leaves and small twigs were the onl}' objects 

 brought up from the bottom ; and there was no indication of 

 life in the water. 



An investigation was next made at the mouth of the brook, 

 which had already begun the formation of a " cone ' ' of clear 

 sand. As the brook itself was open, and the ice of the pond 

 was firm, it was possible, after first cutting away the thin ice 

 along the edge, to make a thorough examination of a consider- 

 able area ; but the sand jdelded no indication of life of any kind. 

 It therefore remained only to find what forms of life there might 

 be in the brook. 



A freshet, that occurred two daj-s previously, had caused the 

 brook to bring down an unusual quantity of clear, 3'ellow sand, 

 which covered the bottom evenly and completely to the foot of 

 the first rapids, about forty rods up the stream. The dredge, 



