Miscellaneous. 315 



water sponge ; and as I understand it, they are thrown 

 out with very great rapidity, and the lakes where these 

 sponges exist remain clouded until there comes a de- 

 cided storm, when the spores are precipitated to the 

 bottom of the lake, and the water becomes perfectly 

 clear again in two or three days. 



"In my testimony in regard to Forest Lake, near 

 Hudson, N. Y., I referred to the fact that this lake 

 was free from cloud, and that from a personal inspec- 

 tion of the lake I had failed to find any fresh-water 

 sponges. In regard to this examination I can only add 

 that the examination of the waters of these lakes was 

 made under a microscope of the highest magnifying 

 power suitable for such a purpose, and that no spores 

 were found except those produced by the fresh-water 

 sponge." 



After this an invitation was extended to me to say 

 something on this subject by a friend, who wrote : "No 

 doubt you saw the different theories about the working 

 of ponds in a late Forest and Stream. What do you 

 think of them? Who is right?" 



My answ r er was : "All are right. There are differ- 

 ent causes for this disturbance of the water. One 

 year the mill-pond at Cold Spring Harbor, Long Is- 

 land, bloomed twice, once in the middle of July, from 

 Nostoc, which lasted four days, when the water cleared 

 and the bass and perch were just coming to their ap- 

 petites, when early in August it bloomed again with the 

 fresh-water sponge, as described by Mr. Van Cleef. 

 During the last bloom many sunfish and some white 

 perch died, and the bass and yellow perch seemed to 

 abstain from food, certainly from baits offered, until 

 September. There is a theory that the pollen from 

 some trees ash, I believe, is one cloud the water at 



