60 FRANK R. LILLIE. 



range, then I would say, as a matter of quite arbitrary judgment, 

 that the free-martins would occupy points 8 to 13, inclusive, pos- 

 sibly encroaching in some doubtful cases on points 14 and 15. 

 The free-martins, in other words, form an exceedingly well- 

 defined group without intergrades to normal female or normal 

 male. Within the group of free-martins there is considerable 

 range of variation which may be classified according to degree of 

 approximation toward the male type, as B. H. Willier (1920) has 

 shown for the gonads. The ducts also would permit of a similar 

 classification, though it is not certain that the classification by 

 gonads and ducts would always agree. 



The absence of intergrades to the female side, and the absence 

 of correlation between the size of the vascular anastomosis and 

 the degree of intersexuality, indicates an " all-or-none " type of 

 reaction in formation of the free-martin; presumably, therefore, 

 the differentiating action concerns a rather definitely delimited 

 period of development and does not require a maximum amount 

 of the male hormones. If this be so, variations of the quantity of 

 the hormones within wide limits would not be significant for the 

 typical reaction. But variation in time of onset with reference to 

 the preceding degree of differentiation of the ovary and other 

 organs of the female may be sufficient to explain in part the range 

 within the free-martin series (cf. Willier, 1920). The matter is 

 discussed further in section 6 (p. 70). 



It is interesting to note that Pezard (1920) concludes that the 

 morphogenetic effects of transplanted testicular fragments on cas- 

 trated cocks also follows an " all-or-none " law ; " as soon as the 

 functional threshold is passed, whatever may be the mass of the 

 active gland, a cock takes on as a whole its secondary sexual char- 

 acteristics. It appears that these manifestations can not be frac- 

 tionated." 



5. On the Occurrence of Seminal Vesicles in the Fcetal 



Free-martin. 



In my study of the anatomy of the fcetal free-martins (1917) 



the existence of seminal vesicles in the stages in question was 



doubted, although they appear in the males in much earlier stages. 



On the other hand, seminal vesicles appear usually to be present 



