430 REPORTS ON THE STATE OF SCIENCE, ETC. 



Vasoligation. — Report of Committee (Dr. F. A. E. Crew, Chairman ; 

 Mr. J. T. Cunningham, Secretary ; Prof. J. S. Huxley) for the 

 experimental investigation of the effects of Vasoligation, <&c., on the 

 Seminal Tubules and Interstitial Tissue of the Testes of Mammals. 



Preparation of illustrated Paper on Results mentioned in last yearns Report. 



The autumn of last year was spent in the microscopic investigation of the vasa 

 efferentia and the different parts of the epididymal tube, and the preparation of 

 photomicrographs to be used as illustrations of a more detailed account of the results 

 mentioned in the report presented last year. One of the most interesting points in 

 the microscopical studies was the confirmation of the fact discovered by previous 

 investigators that the seminal tubules do not terminate by open communication with 

 the initial branches of the rete, but end in conical cellular masses which project into 

 those cavities. The ripe sperms make their way through these cellular plugs into 

 the cavities of the rete. The detailed paper was communicated to a meeting of the 

 Society of Experimental Biology in December 1927, and sent to the editor of the 

 Journal of Experimental Biology in January of this year. It will, I believe, appear 

 in that journal in September next. 



Grafting Experiments. 



I have tried a few grafts of testes from one rat to another, but so far without 

 much success. 



December 6. — Testis from half-grown ta-rat put into scrotum of adult after removal 

 of the original organ. The rat was killed on January 18, 1928. No recognisable 

 remains of the graft were found. 



January 31, 1928. — The host was a young mature male, the graft-rat a smaller 

 male 13-2 cm. long. By operation from the abdomen one testis of the host was 

 removed and a whole testis from the graft-rat fastened by a single stitch to the wall 

 of the scrotum. In the other testis of the graft-rat sperms in movement were found 

 in the epididymis and vas deferens, but sections showed that spermatogenesis was 

 only beguining. The host-rat was killed on March 20, but no distinct remains of the 

 graft were found. 



February 6. — Host-rat a young mature male, the graft-rat 9-2 cm. long, excluding 

 the tail. It was twenty-three days old. Method as before. Sections of the second 

 testis of the graft-rat showed that the organ was quite immature, spermatogenesis 

 not yet commenced. The host was killed on March 20, forty-three days after the 

 operation. The graft was little altered in external appearance but somewhat reduced 

 in size, the original length was 6 cm. ; when examined the length was 5 cm. Sections 

 of the graft showed that the seminal epithelium had the appearance of dead tissue, 

 though the original structure was recognisable, and there was no sepsis ; the graft 

 had evidently not been vascularised. On the other hand, the capsule was thickened 

 and seemed to be alive, though not vascularised. I hope to make more grafting 

 experiments in the future, but since the end of March my attention has been given 

 to experiments on the effect of external temperature on the rat's testes. 



Heat Experiments. 



Various experiments on the effect of an artificially raised temperature on the 

 mammalian testis have been made by previous investigators. Oslund, in the U.S.A., 

 enclosed the scrotum of a ram in woollen materials and a waterproof covering and 

 found, after a period of 80 days, that the seminal epithelium was disorganised. I 

 found it impossible to apply this method to either rabbit or rat, but have successfully 

 carried out another method which involves no interference with the natural condition 

 of the scrotum by artificial covering. The method is simply to keep the animal in 

 a small water-oven in which the level of the water in the double wall is only 2 or 3 ins. 

 above the floor of the chamber. A mercury gas-regulator is placed in the water and 

 connected with a small flame below the oven. The temperature of the water is kept 

 as constant as possible at 37-5° (which is the rectal temperature of the rat). 

 There is an aperture about 1 in. in diameter in the roof of the oven, and the front is 

 merely closed with a piece of perforated zinc. In this way the exterior of the scrotum 

 is exposed to the temperature of the interior of the rat's abdomen, while at the same 



