STEUCTUEE, DEVELOPMENT, AND BIONOMICS OF HOUSE-FLY. 405 
passing uninjured either as eggs or as young larvse into the 
alimentary tract owing to insufficient mastication. Or the 
larvte may have entered per rectum, the eggs having been 
deposited Avhen the patient was visiting one of the old-style 
privies where these flies, especially H. canicularis and 
H. scalaris, frequently abound. These last two species are 
frequently the cause of this intestinal trouble, and it is most 
probable that the larvae enter per rectum. 
Owing to the inability on the part of the observers to dis- 
tinguish the different species of dipterous larvae v/e have 
little information as to their occurrence in these cases. 
Stephens (1905) records two cases. Two larvae were pi’o- 
cured which were stated to have been passed per rectum ; 
one was H. canicularis and the other is described as 
i\I. corvina. The latter larva was stated to possess eight 
lobes on the anterioi- spiracular processes which “ distinguishes 
these larvae from M. domestica, which has seven only.” I 
suspect this larva was M. domestica, which has six to eight 
lobes on the anterior spiracular processes. Some years ago 
a number of larvae which had been passed by a child were 
sent to this laboratory, and I found that they were M . domes- 
tica. In 1905 some eggs taken from the stool of a patient 
suffering from diarrhoea were sent to me and on examination 
they proved to be the eggs of C. ory throcephala. The 
larvae of the small house-fly, H. canicularis, as I have 
already mentioned, have occasionally been found in the stools 
of patients. 
In certain cases the larvae may wander from the mouth or 
alimentary tract and get into the nasal passages or other 
ducts, in which cases complications may ensue and result in 
the death of the patient. 
IX. Literature. 
A few of the more important references included in the two previous 
bibliogi-aphies are repeated here for the sake of convenience. 
1909. Ainsworth, R. B. — “The House-fly as a Disease Carrier,” ‘ Journ. 
Roy. Army Med. Corps,’ vol. xii, pp. 485-498. 
