33 
more graceful than in rickets, the uncalcified areas in the 
epiphysis being only occasionally disorderly; fourthly, 
absence of callus about the fractured bone; fifthly, the 
effect of thyroid treatment upon the young ones ; this has 
not been as satisfactory as can usually be promised in 
human cases. 
It seems worth while to make a survey of our 4225 
autopsies for the purpose of discovering the orders in which 
constitutional bone diseases have occurred with the hope 
that it might indicate something in the line of feeding. 
Before discussing the table it is only correct to state 
that in my own work, and from the records, in that of 
my predecessor. Dr. White, two groups of bone changes 
have been recognized and named, developmental or rickets 
including all the congenital forms or those shown in early 
life, and retrogressive or osteomalacia, an abnormally 
active bone absorption in adult life. There are sub- 
divisions in a pathological sense, such as chondrod^^s- 
trophy, which are not necessary to make since the under- 
lying factors of faulty development or repair are probably 
similar. What was hoped for w^as an indication of faulty 
breeding or feeding. I do not presume to be naturalist 
enough to evaluate fully the effect of captivity and 
possible inbreeding upon specimens but it would certainly 
seem that the primates are most affected in bony develop- 
ment by confinement and artificial food. Whether these 
bone changes occur more here than in the wild of course is 
unknown. The Carnivora are also well represented. The 
absence of the chase and its developmental influence 
must be considered. It is noteworthy that in the Mam- 
malia the orders Ungulata and Marsupialia, of which w^e 
have had a large number, are missing. It is possible that 
the food of these orders in captivity is not so far from the 
natural kinds as is the case with the above named orders. 
Among the Aves one misses the very large order 
Passeres and the Anseres. There seems little upon which 
to comment in this class because orders of different 
habits are represented and lacking. It is noteworthy that 
developmental diseases are all among the Mammalia, 
