88 DISEASE IN WILD MAMMALS AND BIRDS • 
activity at all is showTi by the marrow, no yomig cells 
appearing in the circulation. Clorosis, or green sickness 
of young persons, is a primary anemia and presents itself 
as a moderate cell reduction with a disproportionately 
low hemoglobin percentage. As a disease entity this does 
not occur in the lower animals, so far as I am aware, but a 
very few hemoglobin estimations and a reference to the 
literature would indicate that well marked hemoglobin- 
anemia does occur. 
In so far as the pathology of anemia is concerned we are 
obliged usually to judge by the appearance of the blood 
and tissues, the yellowish pallor of the mucous membranes, 
the condition of the marrow and the amount of pigment ; 
severe rapid cases show hemorrhages and prolonged 
cases have fatty degeneration of the parenchymatous 
organs. For a decision of the primary or secondary 
nature we must judge the accompanying pathology and 
the condition of the bone marrow. 
Secondaey Anemia. 
Secondary anemia can be laid in general to insanitary 
housing or inappropriate diet over a long period, to 
chronic bacterial infection of low grade, to the action of 
blood parasites or those of the bowel which either suck 
blood or elaborate an absorbable toxin, or to single great 
or repeated small hemorrhages. We shall now consider 
the cases at the Garden. Perhaps many other animals 
have had a substandard blood, but these are the cases in 
which the gross appearance attracted close scrutiny in 
this direction. London has had much anemia, probably 
from their reported heavy infestation with parasites, but 
this factor has with us apparently played a small role in 
the production of anemia. 
In Mammalia. 
In so far as the Primates are concerned the one out- 
standing cause of anemia is degenerative disease of the 
osseous system. In both rickets and osteomalacia there 
