PHYSIOLOGICAL PROPERTIES OF GONADS 379 



females and males (psychical modification) and that the external 

 genitals of the female may undergo such changes that they come 

 to resemble the male condition more than the female (somatic 

 modification). 



In animal 67 Bl, the testicle graft reached a large size, both 

 grafts having persisted for slightly longer than nine months when 

 the animal was killed. A rough measurement of the excised 

 grafts, 10 X 7 X 5 mm., represents the entire mass of the tissue, 

 but part of this tissue consists of encapsulating connective tissue 

 and muscle. However, after fixation, paraffin embedding, and 

 sectioning, each of the two grafts consisted of over 600 sections of 

 testicular tissue (cut 10 m thickness). 



The tissue is remarkably wtII preserved for a testicular trans- 

 plant, as the graft consists of compact testicle tissue within which 

 there is no evidence of necrosis. The principal part of the 

 tissue is the region of seminiferous tubules, but in one graft there 

 were approximately 200 sections containing an area of epididymis 

 about one-sixth of an entire cross-section. The other graft con- 

 sisted of a smaller amount of epididymis. This part of the 

 tissue is characteristic of the testicle and need not concern us 

 further. 



The seminiferous tubules were compactly arranged and the 

 intertubular spaces were no larger than under normal conditions 

 (fig. 2). Associated with this the interstitial cells are not more 

 abundant than is ordinarily found in the testicle. In other words, 

 there is no indication of an hypertrophy of the interstitial gland 

 in either of these two grafts. The germinal epithelium has suf- 

 fered some degeneration, as there is an entire absence of spermat- 

 ozoa, spermatids, and in many places of spermatocytes. How- 

 ever, there has not been so great a degeneration of the germinal 

 epithelium as is usually the case, for the tubules contain in many 

 places an epithelium three or more cells in thickness. Many 

 karyokinetic figures occur in the epithelium lining the tubules, 

 and there are also many cells lying free in the cavity of the tubules. 



The grafts from animal 68 Bl differ somewhat from those of 

 animal 67 Bl. In animal 68 Bl the grafts persisted longer than 

 seven months, and are somewhat different in size. The larger 



