12 EDWARD MCCRADY, JR. 



animals were given whole milk and eggs every day, they, none- 

 theless, developed acute rickets. The ones which were adult 

 when brought into the colony occasionally bred once before 

 going sterile. They rarely lived more than a year, and finally 

 died in tetanic convulsions similar to those often associated 

 with osteomalacia and rickets. The young born in the colony 

 appeared normal during the first 80 days (i.e., the nursing 

 period), but then rapidly developed some very characteristic 

 abnormalities. Their legs grew less rapidly than their heads 

 and trunks, and became disproportionately short and bowed. 

 Their heads appeared disproportionately large, and their 

 backs showed kyphosis. Their fur was scrawny, and their 

 teeth abnormal, the canines frequently breaking off. When 

 the thorax was opened, the ends of the ribs showed a typical 

 rachitic rosary. Such animals never attained sexual maturity, 

 and rarely lived as long as a year; though I have on record 

 one case of a male which showed all the rachitic symptoms 

 in an extreme degree, but which survived for 2 years and 

 3 months. 



At first I found it difficult to believe that the animals could 

 really have rickets when they were being fed eggs and milk 

 every day, but as soon as I saw that there was no doubt about 

 the fact that they actually did, I thought the solution of that 

 difficulty would be easy we would simply add cod liver oil 

 to the diet. This was done for 1 year without noticeable, 

 beneficial result. Not only were the diseased specimens not 

 cured, but normal young introduced into the colony from out- 

 side became just as abnormal with cod liver oil as without. 



After trying other vitamin D concentrates, and combina- 

 tions of vitamin D and vitamin A, all to no avail, the next 

 resource was to try forcing the animals to live in the open 

 sunlight. This was decidedly contrary to their natural in- 

 clinations, as under normal conditions they are nocturnal. 

 But even the enforced exposure to sunlight did them no good. 



Finally, I began opening the stomachs of animals just cap- 

 tured, to discover what the wilds ones were eating which the 

 captive ones were not. One such thing which I noticed was 



