PARASITES OF ANIMALS. 97 
but throws down a copious precipitate with a solution of 
nitrate of silver, owing to its strong impregnation with com- 
mon salt. These characters apply to no other fluid in the 
Figure 70. body, whether healthy or morbid.”—Dr. 
aw Murchison. In some cases hydatid tumors 
‘/> situated in the liver and other internal organs 
have been opened from the exterior, with suc- . 
cess, by skillful surgeons, but these operations 
are always dangerous and often immediately 
fatal. The escape of the fluid, with the 
minute cysts and heads contained in it, into 
the abdominal cavity, will give rise to other 
tumors, and thus increase the disease, even if 
death does not immediately result. 
This is eminently a case where “an ounce 
of prevention is worth a pound of cure.” The 
means of prevention are simple, though not 
easy of application inallcases. The first and 
most important rule is to diminish the num- 
ber of dogs to the utmost possible extent, and 
then to keep them at the minimum number ; 
second, avoid as much as possible the prox- 
imity of dogs and sheep ; third, avoid feeding 
dogs with uncooked livers or other offal of 
sheep containing these parasites, or never give 
them such raw food without careful exaui- 
nation ; fourth, avoid too much familiarity 
with dogs, and especially between children 
and dogs; fifth, be careful not to eat lettuce, 
fallen fruit, or other raw food that has not 
been thoroughly washed, both on account of 
this and other parasites; sixth, avoid by all 
means possible the use of impure water, or water liable to 
be contaminated by eggs of parasites and excreta of animals, 
both for household purposes and to supply sheep, cattle, and 
horses, for such water is not only liable to contain echino- 
Figure 70.—Mature Tenia echinococcus, much enlarged. Hearth and Home, 
after Leuckart. 
13 Digitized by Microsoft® 
