98 DISEASE IN WILD MAMMALS AND BIRDS 
or apparently blocking a lymphatic sinus; the Kupffer 
cells do not seem to be heavily laden. 
The extrameduUary formation of blood cells has been 
a matter of considerable interest and study in the human 
being, and as far as it concerns the circulating mono- 
nuclears, the general opinion seems to be that such a his- 
togenesis exists. A decision in the negative is perhaps 
reached by the majority in the case of eiythropoiesis, and 
as far as my observations go, this holds for all mammals. 
It seems worth while, however, to record an occasional 
finding in some birds, especially anemic ones, which may 
be of importance in their erythropoiesis. The adult red 
cell is a clearly formed elUpse with a distinct, deeply 
stained, sharply outlined nucleus of a shape correspond- 
ing to that of the whole cell. Young red cells have a more 
nearly circular outline but almost truly circular nucleus, 
the short diameter being at least proportionately greater 
than is the corresponding short diameter of the whole 
cell; this is also the nucleus whose internal structure 
resembles that of the human plasma cell. Groups of such 
cells have been seen in the interstices of the liver, some- 
times as many as twelve, in a rather orderly formation. 
An excess seems at times \n[sible in the spleen but not in 
orderly arrangement. Observations are under way 
toward determining the relation of this finding to the 
amount of marrow, the condition of the blood and the 
habits of the bird. 
Primary Anemia. 
As already specified primary anemia is apparently 
causeless, aside from the assumption that it is a disease 
of the marrow itself. Since there are only four cases, 
representing three orders and they cannot be grouped as 
could the secondary variety, the individual instances will 
be discussed separately. 
Ring tailed Bassaris {Bassariscus astutus). Adult died after two 
weeks' stay in the Garden with a historj' of general failure of eondi- 
