Abstract
In describing our experiments with partial castration of male animals we stated that very small particles of the testicle left in the body, ranging from a vestige to about half of a testicle, do not increase much (1). No hypertrophy occurred even when the operation was made at a very early age and when the experiment was continued for about eleven months, i. e., till an age when the guinea-pig is already advanced about nine months in sexual maturity. In four experiments of a first series about half, threequarters and seven-eighths of one testicle and the whole second testicle were removed in guinea pigs aged about ten to fifteen days. Two and a half months later the fragments were weighed; they represented only one-tenth to one-fifteenth of the weight of two normal testicles of control animals. But the microscopical examination showed afterwards that we had weighed also parts of the epididymis together with the testicular fragments. It is impossible to clean a small testicular fragment from the surrounding tissues without injury to it; fragments from the upper pole are embedded in fatty tissues or they are adherent to some other organ; those from the under pole are attached to the cauda epididymidis. Sometimes the presence of a testicular fragment was only revealed by microscopical examination. So we decided to calculate in the following experiments the volume of the fragments, sectioning them totally into series. The product of the number of sections and of the thickness of each section gave us the height, the greatest section the basis of a parallelopiped which the different fragments resembled naturally only more or less; the figure arrived at in such a way was reduced to three-quarters.