632 



Growth of Deer Antlers 



ence of spermatozoa in the testes just beginning in July, maximal in October 

 (pi. 1, figs. 3 and 4), and diminishing in December and January. In the speci- 

 mens obtained in March, May, and June the seminiferous tubules are in a 

 state of regression, without any discernible spermatids or spermatozoa. In the 

 specimen obtained on June 9 tubular atrophy is most extreme, the tubules 

 having been reduced to a single layer of cells (pi. 1, figs. 1 and 2). In the May 

 specimen and in the testes of the June 27 specimen the atrophy is not quite so 

 extreme. In the specimen of July 13 regeneration of the tubules is well under 

 way, with the beginning production of spermatids and a few spermatozoa. 



TABLE 1 



Weights of the Testes and Epididymides of Adult Virginia Deer 



Oct. 10. 

 Oct. 10. 

 Oct. 10. 

 Oct. 12. 

 Dec. 10 

 Dec. 17 

 Jan. 21 . 



gm. 



Ill 



100 



66 



105 



72 



92 



49 



Mar. 9 



May 5 

 June 9 

 June 27 



July i.^ 

 Aug. 20 



gm. 



37 

 31 



25 



50 



45 

 67.5 



Regarding the interstitial cells, the impression is gained that the cells are 

 larger, with clearer nuclei and more cytoplasm in the October specimens (pi. 1, 

 fig. 3) than in May or June (pi. 1, fig. 1), when the cells of the interstitial tissue 

 appear to be small with dark-staining shrunken nuclei. No special cytological 

 techniques have been adopted to establish these differences more clearly. 



Male Accessories. The male accessories were dissected and studied histologi- 

 cally in five animals, one each in June, July, and August, and two in October 

 (pis. 2 and 3, figs. 5 to 10). 



Striking changes were observed in the seminal vesicles, whereas in those 

 glandular tissues surrounding the urethra, which we regard as representing 

 the prostate and bulbo-urethral glands, no variations were apparent. Conse- 

 quently we shall limit our presentation to the changes observed in the seminal 

 vesicles. The latter appear to be represented by two tortuous, firm, glandular 



Graph 1, illustrating the periodicity of the antlers, testes, seminal vesicles, and breeding 

 season of the Virginia deer. On the abscissa the months of the year are indicated, beginning 

 with March. The curve for testes is derived from their monthly weights, their individual 

 weights being designated by crosses. The ctnve for seminal ^■esicles is expressed in terms of 

 microns (/j.) representing the height of the glandular epithelium in successive months. 



The periodicity of the antlers is schematically presented for 2-, 4-, and 8-year-old animals. 

 (1) represents the time of onset of antler growth; (2) the completion of antler growth and the 

 shedding of the velvet; while (3) shows the time of dropping of the antler. 



At the top of the graph the results of castration are represented graphically. A, an animal 

 in which castration was performed in Jime; B, in Avhich castration took place in October. 



