Between the lamellæ of peritoneal structure which forms the posterior septum, and which unites the parietal with the visceral layer, there is found a band of grey muscular fibres--first discovered, I believe, by H. Bouley--which exerts a powerful agency in the retraction of the testicle towards the inguinal ring. Behind this muscle, and situated on the internal face of the septum, are found the deferent canal and the circumvolutions of the small testicular artery. Having thus considered the essential points of the anatomical structure of these organs, we shall next seek to enforce the importance of their careful study in reference to the intelligent and skilful performance of the important operation which we are discussing. CHAPTER II. CLASSIFICATION OF THE METHODS -- THREE CLASSES -- FIRST, IMMEDIATE AMPUTATION -- SECOND, AMPUTATION AFTER APPLICATION OF HEMOSTATIC MEANS UPON THE CORD -- THIRD, WITHOUT AMPUTATION, BUT DESTRUCTION OF SECRETING POWER OF THE ORGAN -- SIMPLE EXCISION -- SCRAPING -- TEARING AND TORSION -- TORSION -- FREE AND LIMITED -- ABOVE OR BELOW THE EPIDIDYMIS -- LINEAR CRUSHING -- FIRING. The methods of performing the operation of castration may be variously classified, though in each class a varying number of modes will come under our notice. The first class will include the operations by which, the envelopes having been cut through, the vaginal sac opened and the testicle exposed, the organ is separated by an immediate section of the cord. A number of different processes are included under this head, among which are those of _scraping_, of _tearing_, of _torsion_, of _linear crushing_, or by the _ecraseur_, and of _firing_, or the actual cautery. The second class has also for its first or preliminary step, that of the first, viz., the incision of the bags, the opening of the vaginal sac, and the exposure of the testicle. But instead of removing the organ by the division of the cord, we proceed as a second step, to the application of an apparatus designed to operate by producing compression along the length of the cord, and in this are included but two modes of operating, that by the _ligature_ and that by the _clamps_. The third class, according to our category, presents to our view two further operations, both of which are essentially bloodless and dispense with the incision of the bags, consisting of certain peculiar manipulations which insure the destruction of the testicular structure, and consequently of its secreting power. They comprehend the process of the _crushing of the spermatic cord_, and that of _subcutaneous double twisting_--the _bistournage_ of the French. We now enter upon the consideration of each of the separate modes we have thus enumerated. SIMPLE EXCISION.