18 
BULLETIN 260, U. S. DEPARTMENT OF AGEICULTUEE. 
of such infestation. Ascarids at times enter the appendix and cause 
appendicitis ; they may perforate the intestine and cause peritonitis ; 
they may come up the esophagus and get down the windpipe, with a 
resultant suffocation, or enter the eustachian tube of the ear. These 
are unusual cases for the most part, but they are dangers to be con- 
sidered. There are other unpleasant and dangerous features of 
ascarid infestation, and the uncomfortable certainty that their pres- 
ence is undoubtedly indicative of fecal contamination of food, drink, 
or ingesta of some sort. 
The prophylaxis in this case, as in the case of the previously men- 
tioned worms, depends on keeping dogs free from worms and restrict- 
ing their privileges in the household and in their relationship to 
human beings. 
Fig. 10. — Head of a dog split in half to show three tongueworms (Lingua- 
tula rhinaria), a, in the nasal cavity. Reduced in size (after Colin). 
T ongueworm.— The tongueworm. Lraguatula rhinaria (Linguatula 
se-rrata) (fig. 10). occurs in the adult stage in the nasal passages 
and frontal sinuses of the dog. It is light colored and shows an 
external, ringlike segmentation. The male may attain a length of 
20 millimeters (about three-fourths of an inch) and the female may 
attain a length of 100 millimeters (about 1 inches). The eggs de- 
posited by the female leave the nostrils of the dog in the catarrhal 
secretion occasioned by the presence of the parasite, some of them 
doubtless being sneezed out. and contaminate the vegetation on 
which they at times lodge. Such vegetation may be eaten by cattle, 
sheep, horses, or swine, or if the infested dog has access to a truck 
garden or a family vegetable garden, contaminated lettuce, cabbage. 
etc., may be eaten by man. TThen the eggs get to the stomach the 
shell is digested off, releasing a peculiar embryo which shows by its 
structure that these tongueworms are really related to the mites, a 
group of spiderlike animals. This embryo makes its way through 
