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POPULAR SCIENCE MONTHLY. 



are rather carrion species. Other forms were taken, but either their 

 household occurrence was probably accidental or from their habits 

 they have no significance in the disease-transfer function. 



It appears plainly that the most abundant species breeding in or 

 attracted to dejecta do not occur in kitchens and dining rooms, but 

 it is none the less obvious that while the common house-fly, under 

 ordinary city and town conditions as they exist at the present day, 

 and more especially in such cities and towns, or in such portions of 

 cities as are well cared for and inhabited by a cleanly and respectable 

 population, may not be considered an imminent source of danger, it 

 is, nevertheless, under other conditions a factor of the greatest im- 

 portance in the spreading of enteric fever. 



The house-fly undoubtedly prefers horse manure as a breeding 

 place. We have shown that it is not one of the most abundant species of 

 flies breeding in or attached to human fasces, but, in the course of the 

 observations made in the summer of 1899, we have definitely proved 



Fig. 7. Sarcophaga assidua— enlarged. 



the following facts relative to the house-fly, and in the statement of 

 these facts it must be remembered that every specimen has been 

 carefully examined by an expert dipterologist, so that there can be 

 no mistake: 



(1.) In the army camps the latrines are not properly cared for 

 and where their contents are left exposed, Musca domestica will, and 

 does, breed in these contents in large numbers, and is attracted to 

 them without necessary oviposition. 



Such observations were not made by the writer at the concentra- 

 tion camps of 1898, but were made at the summer camps of the 

 District of Columbia Militia, during the summers of 1899 and 1900. 



The contrast between the conditions here observed and those which 

 existed at the great army camp at the Presidio, San Francisco, Cali- 

 fornia, as observed by the writer through the courtesy of Surgeon- 

 General Sternberg and Colonel W. H. Forwood, surgeon in charge of 

 the Department of California, in the late autumn of 1899, was most 



