178 PROCEEDINGS OF THE AMERICAN ACADEMY 



degrees of fineness, from coarse to very fine, we have the water on 

 one hand free from taste, while the filters retain the matter which 

 rendered the water impure. A portion of this matter placed in pure 

 water gives to it the taste of Cochituate water, while another portion 

 under the microscope presents only living and dead crustacea. Dr. 

 Bacon has kindly recorded his observations, and allowed me to ap- 

 pend his account of them to this paper, 



" The experimental evidence, having proved the origin of the so- 

 called ^aste of the water to arise from the presence of an odorous 

 oil contained in the bodies of carnivorous crustacea, there are two 

 practical points to which attention should be called. 



" Compared with the water of a pond or lake, where a natural 

 balance exists between the fish, crustacea, infusoria, and subaqueous 

 plants, this water is contaminated by an oily food, which affords sub- 

 sistence to an unnatural number of crustacea. To restock the lake 

 with several varieties of fish, and by legislative action to protect their 

 growth and increase, seems the proper course to be pursued in cor- 

 recting the evil. If efficiently carried out, such steps may so improve 

 the quality of the water, that this source of supply will have all the 

 purity of the best known sources, without the variations observed. 



" While the impurities exist, it is prudent for families to use for 

 drinking, and, if possible, for cooking, only such water as has been 

 passed through a filter. Even coarse, temporary resorts of this kind 

 will remove much that is offensive, while the better filters will com- 

 pletely purify the water." 



Dr. J. Bacon exhibited under the microscope specimens of 

 Cyclops and Daphnia in Cochituate water, containing visible 

 globules of oil, to the great abundance of which was referable 

 the present impurity in Cochituate water, as suggested by 

 Dr. Hayes ; and read the following paper, entitled " Observa- 

 tions on the Oil contained in the Crustaceans found in the 

 Cochituate Water." 



" The occurrence of numerous transparent globules in the bodies 

 of the minute crustaceans found in the Cochituate water first at- 

 tracted my notice in the spring of 1854, and I then ascertained by 

 chemical tests that they consisted of oil. Supposing that they were 

 ova in some stage of development, and were probably well known to 

 naturalists, no further observations were made until the bad condition 



