450 DISEASE IN WILD MAMMALS AND BIRDS 
All these types of toxins will destroy if they act acutely in 
suflScient concentration ; or as is more conunon, if they act 
persistently over long periods, or at oft recurring inter- 
vals they will cause serious injury to the tissues coming 
in contact with them, and have a part in the production 
of cirrhosis of the liver, chronic nephritis, myocarditis, 
arteriosclerosis, etc. 
All foods have a limit beyond which they are excreted 
untouched or imperfectly oxidized. Many of these partial 
oxidation products of protein are in themselves toxic and 
may also be a source of these degenerative organ condi- 
tions. The pathological material studied by us showed a 
marked decrease in gastrointestinal diseases in close asso- 
ciation with the more hygienic care of the meat foods. 
Always associated ^\dth the protein foods are the 
nucleoprotein complexes, which are split by both bacteria 
and digestive juices into globulins and nucleic acid, and 
then through the agency of a special enzjine, into purin 
bases and uric acid, in which forms they are excreted in 
the urine and feces. The oxidation of purins is 
never complete. 
Gout, representing the pathology of purin metabolism, 
is a paroxysmal inflammatory disturbance, due to the 
deposition of sodium urates in the joints or in the internal 
organs, usually accompanied by a fibrosis especially in 
the liver, kidney, arteries, etc. The disease occurs almost 
exclusively in birds. Isolated cases have been described 
in dogs, horses and hogs, but among lower animals it is 
undoubtedly very rare. In birds it is most frequent in the 
carnivores — 4 per cent., as against 0.02 per cent, in all 
other groups. It is higher in fish-eating birds than among 
the flesh-eaters. The avian gout is usually of the visceral 
t}TDe and was most marked in its distribution over the 
organs in the Anseres and Psittaci, birds whose diet 
apparently is not unduly heavy in nucleoproteins, but 
whose tract approaches the carnivorous type. The only 
