The recent advances in endocrinology have been so great that there is hardly a medical specialty that it does not touch and influence to a greater or lesser degree. Hence, I feel that as an endocrinologist I have to make no apologies for appearing before you to-day. I was asked to give you a short address on the physiology of the pituitary gland, but I felt that a paper by my colleague, Dr. Hector Mortimer, 2 to which I might say a few words by way of an historical introduction, would be of more value to the members of your Society. Dr. Mortimer has been able to prove that hormones affect bone growth. The idea is not new, but Dr. Mortimer's observations will, I think, give conclusive evidence of the profound effects of certain hormones on skeletal development, differentiation, and architecture. Before speaking of hormones in particular, let me call to your mind the older observations on the profound effect at times of environmental conditions on the bony structures. Most important of these factors is prob...