366 DISEASE IN WILD MAMMALS AND BIRDS 
be covered by a single row of osteoblastic cells. The 
intertrabecular spaces are large, irregular and filled with 
a delicate alveolar tissue containing only a minimal 
number of normal bone marrow cells, large capillaries and 
no giant cells. Periosteum may be of usual thickness; 
the bone immediately beneath is spongy. The sclerosis 
of the bone in its densest areas is entirely due to the ossi- 
fication of spindle cells which have remained in the place 
of the original marrow of the bone. As a whole the bone 
is nowhere normal in amount or proportion but the small 
Haversian systems are properly made, the abnormality 
being chiefly due to cellular and fibrous gro^vth around the 
large lamellae which at times is normal in amount but 
usually much in excess. In places this consists wholly of 
fibroblasts, at others of giant and round cells very sug- 
gestive of sarcoma. All histologists apparently agree 
that Paget 's disease starts as a resorption of already 
calcified bone." 
These data seem to supply ample evidence that the 
autopsy diagnosis of Paget 's osteitis deformans was cor- 
rect. While the anatomy and course and chemical changes 
presented by these monkeys do not settle the causation of 
the disease, they offer very definite suggestions which 
Dr. Corson-'White summarizes in the following cau- 
tious conclusions. 
** Many of the cases of Paget 's disease first came 
under the observation for fractures, accidents common in 
osteomalacia but very rare in developed cases of osteitis 
defonnans. Early cases all presented diarrhoea, which 
was present in all the early human cases seen, and in all 
the cases reported in monkeys. This symptom was men- 
tioned in fourteen of the cases from the literature. It was 
also a constant symptom in primate osteomalacia. The 
diet of these monkeys was exceedingly low in those sub- 
stances essential to bone development, and Sherman has 
shown that the calcium balance is regulated to a certain 
