DROSOPHILA IN STERILIZED MILK 45 
vessels with unclean and therefore insanitary water. It is, 
however, not to be denied that the flies may have gotten into the dirty 
bottles containing a residuum of milk before they were filled. For this 
reason the milk in the bottle must be regarded as questionable from a 
hygienic viewpoint.” 
It was this view which first impressed itself upon me. A more 
careful examination of conditions has convinced me that it is incorrect 
and that the presence of the puparium is no index of the thoroness of 
the sterilizing process which the bottles undergo before they are filled. 
Indeed it would seem clear that, as in my experience, the failure of 
Fettick to rear the flies was due to the fact that the pupae had been 
killed by the washing process to which the bottles were subjected. 
It must not be overlooked that the presence of such organisms is 
but a readily visible illustration of the gross contamination which may 
occur in milk bottles in homes and in business places. To one who has 
seen conditions it is almost inconceivable that a housekeeper should 
be willing to return bottles in the filthy condition in which they are 
sometimes received by the dairies. It certainly affords argument for the 
enforcement of ordinances requiring milk bottles to be washed when 
emptied. il 
My thanks are due to Mrs. Helen Sanborn Chapman for the faith- 
ful manner in which she has executed the accompanying drawing of the 
puparium. Iam also obligated to Mr. C. Kx. Linton, of the Minneapolis 
City Health Department, who first brought this subject to my attention 
and whose co-operation made it possible for me to study conditions in 
Hly| 
the local distributing stations. 
