THE MALE GENITAL TRACT. 817 



my hands, given good results. I can also recommend eosin with logwood for 

 the same purpose, as deserving a trial. 



The chloride of gold method is still the only available one for bringing out 

 the ultimate nerve-terminations. Some of the most beautiful and convincing 

 specimens in my possession are sections of the testicles of young rats, which 

 were hardened in chromic acid and then stained with chloride of gold, in 

 strict accordance with the rules laid down by Cohnheim. Such specimens 

 will show improvement during the first twelve months. It was certainly 

 a step in advance when Lowitt introduced his formic acid method, by which 

 we are enabled to allow the reduction of gold to take place in a dark- 

 ened bottle. This method, in some cases, gives better and more uniform 

 results, and reduces the metallic precipitate, so often found on the surface of 

 sections, to a minimum; but the destruction of the epithelia which this 

 process entails is not in all cases desirable. 



In hardening, staining and preparing tissues generally, I have preferred to 

 cut up the testicles into sections of from two to three millimeters in thickness, 

 and, instead of the imbedding methods, I found it much more convenient to 

 use the freezing microtome for fine sections. In so doing two things are 

 avoided viz. : shrinkage and the introduction of foreign material. 



Being obliged to use high powers for the recognition of the ultimate ter- 

 mination of the axis-fibrilla3, the thinnest sections were chosen and mounted in 

 glycerine to which one-third of its volume of distilled water had been added. 

 Specimens stained with osmic acid and picro-carmine can be advantageously 

 treated after the plan proposed by E. Neumann, which is that of temporarily 

 mounting in glycerine mixed with muriatic acid in the proportion of two hun- 

 dred parts of the former to one of the latter, and carefully watching until the 

 orange-red coloration has been reduced to the nucleus, then washing out 

 thoroughly in distilled water. 



Anatomists agree that the nerves of the testicle are derived from the sym- 

 pathetic. As long ago as 1834, Joseph Swan* gave a very good representation 

 of the spermatic plexus of nerves. According to Robert B. Todd,t the nerves 

 of the testicle are derived chiefly from the renal plexus, but partly also from the 

 superior mesenteric and aortic plexuses. These nerves then descend in com- 

 pany with the spermatic artery to the cord, where, being joined by branches 

 from the hypogastric plexus which passes along the vas def erens, they form to- 

 gether the sperm-plexus. The branches of this plexus are intermingled with 

 the vessels of the cord, and ultimately terminate within the substance of the 

 testis. A few twigs may also be traced to the coverings of the gland. Sappey t 

 recognizes two sources of nerve-supply, namely, one from the plexus accom- 

 panying the spermatic artery, which, he says, alone penetrates into the sub- 

 stance of the testis, and the other from the plexus surrounding the vas 

 deferens, which, according to his view, terminates in the epididymis. 



In regard to the nerves running within the structure of the testis, I can 

 corroborate the views above detailed, namely, that none but non-medullated 

 nerve-fibers are found ; and I can add that their characteristic arrangement is 

 in the shape of plexuses. These, when found in the neighborhood of the 

 larger arterioles, are, of course, large in proportion. As they pass on, always 



* "A Demonstration of tlie Nerves of the Human Body," London, Plate V. 

 t " Cyclopedia of Anatomy and Physiology," vol. iv., pt. 2, pp. 982. 

 | " Anatomie Descriptive," tome4, p. 614. 



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