Tin. PINEAL GLAND \M> Tin; 0ONAD6 777 



granules, staining black with osmic acid, are also present in tin- cyto- 

 plasm. The degree of developmenl of the interstitial cells varies in dif- 

 ferent animals, being marked in the <'at ami man ami ill-marked in the 

 rat and rabbit. In animals which slmw seasonal changes in Bexnal activ- 

 ity, the cells are mosl prominenl between the periods of sexual activity, 

 when the semeniferous epithelium is less evident. They also become 

 prominenl in eases where the Bemeniferous epithelium is atrophied, 

 either as a result of disease or following I iu r ;it inn of the vas deferens done 

 iii such a way that the artery and nerves to the testicles are not included 

 in the Ligature. When the testicle or a portion of it is grafted into 

 another part of the body, the Bemeniferous epithelium degenerates, but 

 the interstitial cells remain alive and become quite prominent. It is 

 believed that the interstitial cells are responsible for the production of 

 an autacoid thai has to do with the development of accessory sexual 

 characteristics. 



'/'Ik i ffii-ts of castration are not significant in animals below the verte- 

 brata. In all of those, how-over, they are very pronounced. The . 

 trated male frog fails to show development of the thumb pad, hut this 

 development immediately ensues if portions of testis from another frog 

 be placed in the dorsal lymph sac. Tn birds the results are more pro- 

 nounced; in the Castrated male chick the comb, spurs, wattles, etc., fail to 

 develop, hut will usually do so if some testis from another bird is trans- 

 planted into it s tissues. In mammals tho effects are most Striking in 

 animals that develop marked male characteristics, such as the growth 

 of antlers in stairs. These fail to develop properly and are prematurely 



sheil after castration. In man also, ;is is welhknown from a study of 

 eunuchs, castration has a very profound effect. Hair fails to grow on tho 

 face; the larynx remains undeveloped; the epiphyses are a long time in 

 Ossifying, so that the stature may become great, hut at the same time 

 the limb hones may he more delicate than Usual ; the sutures of the skull 



are slow in closing; and the whole architecture of a castrated male comes 



to he very like that of the female. Confirmatory evident f tho infiu- 



ence of the testicles on the developmenl of secondary sexual character- 

 istics is afforded by the observation that malignant tumors of the tee 

 in hoys are associated with the premature development of the secondary 



sexual characteristics, and thai these may recede after the removal of 

 tho tumor. 



As a result of castration, interesting changes have also been observed 

 in other ductless glands. Thus, the suprarenal cortex and tho thymus 

 become enlarged, whereas the thyroid ami pituitary become atrophied. 

 The metabolic fund ions also l> ( me tardy, as is e> idenced by i ncy 



to the deposition of fat. 



