— 
cearse 
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 crustaceans. 
Dr. Bacon has kindly recorded his observations and allowed 
me to append his account of them to this paper. 
Observations on the Oil contained in the Crustaceans found in 
the Cochituate Waier, by Joun Bacon, M.D. 
The occurrence of numerous transparent globules in the bodies 
of the minute crustaceans found it ochituate water, first 
attracted my notice in the spring of 1854, and I then ascer- 
tained 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 wer 
made until the bad condition of the Cochituate water attracte 
public attention ; when I called the attention of one of the chem- 
1Sts employed to analyze the water to the presence of this oil 
and suggested that it might be the canse of the evil. But it 
did not appear probable to either of us that a small amount of oil 
Could occasion so serious an effect: and thus the matter rested 
Until the commencement of the present year, when Dr. Hayes 
placed in my hands for microscopical examination the gelatinous 
Substance collected by him on cloth filters. The microscope re- 
vealed an abundance of oily globules, in the bodies of the Cy- 
clops and other minute erustaceans, of which the mass on the 
filter chiefly consisted, and the source of the oil obtained in his 
experiments was ‘at once evident. At this time, early in January, 
very few Conferva and other vegetable organisms were found. 
The empty silicious shells of various Diatomacee were abundant 
ntough the carapace which is mostly transparent; and it is 
tinguished by its high refractive power and other optical charac- 
ters from the other contents of the shell. It can also be extracted 
by ether, and still more satisfactorily, by strong alcohol from the 
ody of the animal, while in the field of the microscope. The 
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