36 
prairie dog showed such anatomical changes (ascites, &c.) 
as to indicate that this parasite was the cause of death; 
and furthermore, an Enghshman, Bancroft, has proven 
the point experimentally by feeding trichosoma eggs 
to another rodent, the white rat, which regularly died 
in a few weeks. It is entirely possible, in fact probable, 
that the prairie dog contracted the disease in these 
gardens, for the liver of several rats caught here were 
similarly affected as were also those caught in the Phila- 
delphia General Hospital. From these animals, eggs 
were secured and are now in course of incubation prepara- 
tory to feeding to rats and prairie dogs obtained for 
this experimental purpose. 
It is not possible to determine how many others of 
our prairie dogs are similarly affected because the eggs 
are not passed via the intestine, so that examination 
of the dejecta is useless. It is necessary that the animal 
die and that the egg incubate at least three months 
before they can successfully develop in a new host. This 
was shown by Bancroft for rats, but he does not appear 
to have considered the possibility of disseminating the 
disease among wild rats as an exterminative measure. 
It is this that makes the present finding an interesting 
and promising one not only against rats but other un- 
desirable rodents. Prairie dogs, for instance, are con- 
sidered a nuisance in their natural habitats by reason 
of the burrows they make, and California squirrels, like 
rats, are susceptible to bubonic plague and so many 
act as porters of human disease. 
Hookworm Disease (Uncinariasis). 
Mention has already been made by Dr. Fox of a paper 
published from the laboratory showing the distribution 
of uncinaria (hookworms) among our animals. The 
following table is reproduced from that article as showing 
more concisely than words just what animals were affected 
and to what degree. 
