396 INTERNAL SECRETION 



entire spermatic cord ; and that ligature of the vas deferens 

 destroys the generative portion of the gland only. 



The changes of puberty are ushered in by an enormous de- 

 velopment of the cells of Leydig. In species with well-marked 

 rutting periods, this phenomenon invariably precedes sperma- 

 togenesis ; it is very marked in the testicle of the mole (Tandler). 



Histological investigation shows that, in the testes of old 

 animals and of senile man, there is distinct diminution in the 

 number and size, together with atrophy, of the cells of Leydig. 

 The latter is expressed by the remarkable profusion of pigment 

 in the cytoplasm and the absence of other enclosures. 



The observations which have been made in connection with 

 cryptorchidism are to be regarded as direct proof that the incep- 

 tion and development of the secondary male characteristics are 

 exclusively controlled by the interstitial cells of Leydig. 



In addition to these findings, which are common to the large 

 majority of cryptorchids, further evidence is supplied by those 

 rare instances in which cryptorchidism in man is associated with 

 feminine secondary characters. Histologically, these cases show 

 complete sclerosis of the testis, while at the same time the cells 

 of Leydig are reduced to a few scanty groups (Felizet and Branca). 

 According to Bouin and Ancel, cryptorchidism is peculiarly in- 

 teresting in pigs, such animals showing considerable difference in 

 the secondary sex signs, in sexual instinct, and especially in the 

 development of the genital tract. These differences depend upon 

 variation in the weight of the testicles, which in its turn results 

 from the different degree of development of the interstitial gland. 

 The genital tract is well developed in proportion to the number 

 of cells of Leydig which are present in the testes. In regard to 

 genital organs, sexual instinct, and somatic characters, the 

 cryptorchidic pig stands midway between the normal and the 

 castrated animal. As a general rule there is insufficient develop- 

 ment of the cells of Leydig in the testes, and the place which the 

 animal occupies between the. two extremes is determined by the 

 degree of this insufficiency. 



Tandler and Gross (1908) made use of the elective properties 

 of the Rontgen rays to demonstrate the independence of the 

 secondary characteristics of sex of the function of the generative 

 portion of the testicle. 



Since Albers-Schonberg, in 1903, reported that the Rontgen 

 rays exercise a profoundly deleterious effect upon the male genital 

 glands, numerous communications npon this subject have made 

 their appearance ; these were concerned, partly with the results of 

 experiments and partly with clinical material, but they all con- 

 firmed Albers-Schonberg's findings. Experimental work is 

 described by Selden, Buschke, Krause and Ziegler, Villemin, 

 Bergonnie and Tribondeau, Regaud and Dubreuil, Herxheimer 

 and Hoffmann. Clinical material is contributed by Philipp, and 

 bv Brown and Osgood. 



