In this work the role of the blood vessels surrounding the epiphysial growth plate has been studied. The nutritional dependence of the proliferative cells on the epiphysial vessels has been established whereas the metaphysial vessels were seen to take part in calcification and ossification at the metaphysis.

As it does not seem likely that the blood circulating in the two systems of vessels had a different constitution, particularly in hormones and vitamins, it seems permissible to assume that it is the characteristics, particularly in shape and number, of such vessels that make growth the orderly process it is, with the repeated birth of a cell at the top of a column and burial at the bottom end. But, despite this undeniable role of the vessels, growth depends on the ability of the cartilage cell to form a matrix which, in due course, will be avid for apatite crystals.

The blood supply of the vertebral column of the rabbit has been studied. A description of the embryological development of the blood supply is followed by a description of the blood vessels supplying the adult vertebra.

The main findings in this experimental work on rats fed on lathyrus odoratus (sweet-pea) meal are as follows:

1. Growth is retarded.

2. The growth plate is disorganised and normal ossification at the metaphysis is interfered with.

3. The small blood vessels are seriously affected and probably contribute quite largely to the disorganisation and lack of calcification.

4. Alkaline phosphatase activity is increased.

5. Raising of the periosteum and laying down of new bone result in exostoses. The possible underlying etiology and the role of cement substance, endocrine factors and the blood vessels are discussed.