454 DISEASE IN WILD MAMMALS AND BIRDS 
but proves entirely inadequate when fed to an omniv- 
orous tract. 
Seed Diet. 
Closely allied in general character to the diet of suc- 
culent vegetables are the seed diets, eaten only by birds 
and having no parallel among mammalian foods. All 
seeds, in contradistinction to tubers, contain true proteins 
which, however, are of poor qualitj^ because of the defi- 
ciencies in the aminoacid content. They are as a rule low 
in the fat vitamines and in the amount of calcium, sodium 
and clilorine carried. In three pathological conditions 
only do these birds show any oversusceptibility : (1) Sore 
eyes, (2) acute enteritis, (3) osteomalacia. Sore eyes 
were frequently noted in this group. The lesions were 
very like those described in animals deprived of the fat 
vitamine, which was present in this food in very small 
amounts or entirely absent, thus giving a very plausible 
explanation of this condition, especially as in some of the 
cases no other cause could be found. Gastric disease of 
any type is rare in this group because the food at the 
gastric stage is highly resistant to bacterial action. In 
the duodenum, however, the conditions are early changed 
because the bacteria carried with the food through the 
stomach become active in the presence of available carbo- 
hydrate and protein decomposition products. 
Osteomalacia is confined almost as exclusively to the 
seed-eating birds as it was to the omnivorous mammals, 
and it is also associated with the same deficiencies, cal- 
cium and phosphorus (cf. Tables 19 and 20). It is also 
interesting to note that these two diets, the omnivorous 
and seeds, yield the greatest number of cases of tubercu- 
losis. Mammals showed 32.6 per cent., as against 5.8 per 
cent, in all the other dietarj^ groups, an observation which 
becomes more striking when man is added to the omnivo- 
rous group. Seed-eating birds showed 17.2 per cent., as 
against 6.4 per cent, in other groups. In both diets the 
