72 DISEASE IN WILD MAMMALS AND BIRDS 
we have made such a separation at this laboratory. Here 
is not the place to engage in the academic discussion of 
the nature of the process, but I msh to state that col- 
lectively the changes as seen in such lesions in the lower 
animals are more degenerative than productive, and that 
we have never seen true ulcerative atheroma as it not 
uncommonly appears at the autopsy table in any large 
hospital. This disease of the vascular walls has long 
been attributed to alcohol, gout, syphilis and other such 
prolonged intoxications to which we might apply the light 
term of ''toxins of civilizations." Too little credit, or dis- 
credit has been given to chronic intestinal disorders, 
overeating, and overdrinking of ordinary fluids, to 
entirely incorrect diets, and to chronic bacterial diseases. 
Even though the exact counterpart of the disease in man 
does not occur in lower animals, we shall see the probable 
association with food and with habits, in a manner 
discordant mth former teaching of the causation of 
the disease. 
The group to which the name degenerative arteritis 
has been applied is, as has already been indicated, more 
productive than the analogues seen in the human being, 
but indeed it is questionable whether the lesions even in 
the lower animals are not more degenerative than pro- 
ductive. Since, however, chronic arteritis is always asso- 
ciated with damage to the elastic and muscular fibres of 
the media as well as \vith fatty change and overgrowth 
of the intima, all the deforming and degenerative cases 
will be classed together. 
The general picture in mammals is one of diffuse 
rather than of plaque-like thickening, but well outlined 
raised or depressed areas are encountered. In the aorta 
and larger branches one may find irregular streaking and 
loss of elasticity with fairly clear, pale yellow or gray, 
flat sections of distinct opacity. Rarely these may con- 
tain calcareous matter, a change most often seen in the 
carnivores. The lesions are very largely limited to the 
