THE DOG AS A CARRIER, OF PARASITES AND DISEASE. 17 
do the dozens of other dangerous and improper things that some dogs 
are allowed to do. 
The presence of one or a few of these tapeworms in man probably 
occasions very little inconvenience as a rule. At the same time the 
tapeworm has an unpleasant habit of burrowing through the intesti- 
nal mucosa, thereby destroying its integrity and exposing it to the 
attack of any pathogenic germs that may be present in the intestine. 
The same burrowing habit makes it difficult to remove successfully 
the entire worm with the head, and a failure to remove the head, 
owing to its being buried in the mucous lining of the intestine, results 
in the subsequent development of new tapeworm segments from the 
head and a renewal of infection. At its best, a tapeworm is a thing 
unpleasant to contemplate as an inhabitant of our intestines. The 
presence of the tapeworm under discussion here is, moreover, 
evidence of careless or unclean habits on the part of the person 
infested. 
Prevention requires that the unwarranted liberties and freedom of 
the dog be curtailed; that he be kept free not only from tapeworm 
but from such external parasites as fleas and lice. The accomplish- 
ment of the latter measure calls for keeping a dog clean and restrain- 
ing him so that he will not be allowed to run at large with vagrant 
flea-infested and lousy dogs. 
Roundworm. — Among the other parasites of the dog there is a 
nematode or roundworm, scientifically known as Toxascaris Mmbata, 
which, like the tapeworm just mentioned, may occur in man in the 
same form in which it occurs in the dog. This worm does not have 
an intermediate stage in another animal, but is conveyed directly 
through the eggs produced by the female worm, which eggs normally 
convey the infection from a dog back to the same or another dog, 
either in contaminated food or water or as the result of the con- 
tamination of the skin and the subsequent cleansing of the skin by 
means of the tongue. 
Under the conditions of unwarranted association and familiarity 
with dogs already mentioned, eggs of this parasite and of an allied 
parasite in the cat may be ingested by man, and especially by chil- 
dren, and subsequently develop into the adult worm in the intestine. 
These worms may produce unpleasant results. The entire group of 
ascarids are notorious for their wandering habits. They not in- 
frequently travel to the stomach and produce vomiting, in the course 
of which the worms may be brought up. It is hardly necessary to 
say that the vomiting of worms 4 or 5 inches long is a distinctly 
unpleasant experience, and this is one of the least unpleasant results 
