116 BENJAMIN H. WILLIER 



X-rays (Regaud, '10), feeding a diet deficient in water-soluble 

 vitamine (Allen, '19), eliminating the sjnnpatlietic nerve supply 

 (Kuntz, '19), transplantations (Moore, '19), etc. 



These cases (at least the experimental ones) all indicate that 

 the atrophy of the male germ cells is accompanied by the hyper- 

 trophy of the interstitial cells. In the free-martin gonad there 

 is no atrophy of the male germ cells to accompany the hyper- 

 trophy of the interstitial cells. It would therefore appear that 

 the increase of the interstitial cells is not necessarily associated 

 with the phenomenon of the degeneration of the germinal cells. 

 There may be some more fundamental changes in metabolism, 

 which are responsible for the observed modifications. There 

 is some evidence that metabolic changes result in certain struc- 

 tural modifications in the testis, as, for instance, the cyclic changes 

 in hibernating animals (Rasmussen, '17 and '18). It is problem- 

 atical whether changes in metabolism bring about the degener- 

 ation of germ cells or the absence of germ cells brings about 

 changes in metabolism 



A question of considerable interest arises as to the relation of 

 the interstitial cells to the sexual instincts and to the secondary 

 sexual characters in the free-martin. In mammals having 

 cryptorchid testes the typical sexual instincts are manifested 

 and are apparently associated with the functioning of the abundant 

 interstitial cells (Hanes, '11; Whitehead, '08). Since the struc- 

 ture of the sex-cord region of the free-martin gonad resembles 

 in essential details the sex-cord region of a cryptorchid testis, 

 it might be expected that the free-martin would have the usual 

 sexual instincts of a male. This is apparently not the case, at 

 least so far as the literature discloses. According to the accounts 

 of Lundberg ('64), Zschokke ('00), Hunter ('86) and Magnusson 

 ('18), free-martins fail to exhibit sexual instincts. Hart (10) 

 states concerning one of Hunter's free-martins on page 231: 

 "This animal was seven years old; went with the cows and bull; 

 never showed any desire for either." Zschokke states that in 

 the Alps the free-martin is used like the ox as a beast of burden, 

 because it is strong and tame, or it is fattened for the market. 



