2 BULLETIN 597, U. S. DEPARTMENT OF AGRICULTURE. 
right sac differs in having a soft membrane with an epithelium 
formed by a single layer of cells. 
G. intestinalis larvee are practically always found attached in the 
left sac, and it is the opinion of Dr. Guyot that this portion affords 
the most stable point for larval attachment. He thinks that cases 
are exceptional in which larve maintain themselves in the right sae. 
This, however, does not explain the attachment of G. nasalis in the 
duodenum and to the walls of the pharynx, nor does it account for 
the attachment of G. haemorrhoidalis in the right sac of the stomach, 
in the duodenum, or in the rectum. As has been mentioned by 
Dr. Guyot, the reason for attachment in certain regions of the diges- 
tive tract will remain a mystery until the manner in which larvee 
are nourished is ascertained. 
Various investigators have been unable to discover white or red 
corpuscles of the horse in the pharynx and other alimentary portions 
of the larvee. Clark believed their food was probably the chyle, but 
Guyot rejects this explanation, as larve in the pharynx are located 
where this could ‘not possibly be utilized. As Oestrus ovis larvee 
nourish themselves with the mucus secreted by the mucosa of the 
nose and frontal sinuses of sheep, and as those of Hypoderma utilize 
the pus of the abscesses which they create by their presence in cattle, 
he believes it permissible to suppose that those of Gastrophilus find 
nutriment in the inflammatory products of the gastric mucosa. 
It would appear, from observations, that Gastrophilus larvee some- 
times feed upon the blood of the animal, although they are not de- 
pendent upon it for subsistence. The red and maroon color of G. 
intestinalis and G. hemorrhoidalis, with their attachment upon 
points other than the mucosa of the left sac, would bear out this 
hypothesis, which is further supported by the fact that G. haemor- 
rhoidalis when fully developed in the rectum still retains a pinkish 
color. 
THE ALVEOLAR LESIONS OF THE STOMACH. 
In Dr. Guyot’s examinations of lesions caused by the attachment 
of larve to the mucosa of the left sac, the muscular coat was not 
damaged. ‘The condition found was merely a localized inflammation 
around the point of larvai attachment, in which the derma had been 
invaded by leucocytes. He assumes that this is only the common 
inflammatory reaction which would be normally produced around 
any foreign body. 
In following these studies Perroncito found that the bottom of the 
alveolus varied in size and became the seat of a more or less remark- 
able inflammatory process. This produced a thickening of the walls 
of the stomach and finally the disappearance of the muscular tissue, 
which becomes hard and compact, preventing the normal functions of 
