THYMECTOMY IN THE RABBIT.

Thymectomy in the rabbit is a comparatively simple procedure. The open method described above offers many advantages over any of the closed methods and success depends largely upon the observance of a few precautions; chief among these is the avoidance of haste and the observance of aseptic technique. The operative mortality in our series of rabbits was 10 per cent and there was an additional loss of useful animals, due to secondary complications, amounting to 16 per cent. Among the last 29 rabbits, however, there was only 1 operative death, in an old animal, and 2 cases of slight infection. It appears, therefore, that with some experience the operation can be carried out successfully in nearly all animals, especially so if comparatively young rabbits are used. Old rabbits present greater difficulties on account of the presence of dense fibrous tissue within the field of operation. While the animals of this series showed no immediate symptoms or alteration in physical condition that could be referred to thymoprivia, it is not to be assumed that removal of the thymus is entirely without effect even on rabbits of mature age. Our observations on the reaction of thymoprivic rabbits to disease show that this is not the case and that in all probability decided effects can be demonstrated if the problem is approached on another basis. The object of the present investigation was, however, to determine whether the thymus could be completely removed from rabbits of certain ages without producing any serious disturbance of health which would interfere with their use in other experiments or complicate the interpretation of results. It was found that this could be done.