THE ORIGIN OF GYNANDROMORPHS. 115 



POSTSCRIPT. 



Professor F. R. Lillie has called my attention to two important papers on 

 freemartins. It appears that Tandler and Keller^ had already published, in 

 1911, the essential facts relating to the vascular connection between the 

 embryos in utero, leading to the development of the freemartin out of the 

 female member of the united pair. They had also shown that the embryos 

 come from two eggs, Magnussen'^ in 1918 has described a considerable 

 number of cases of freemartins. He regards both individuals as having 

 started as males, and compares the usual rudimentary condition of the testes 

 of the freemartin with that of a cryptorchid testis. He adduces no evidence 

 of importance in favor of his view that the twins started as males, while 

 Lillie 's evidence is convincing in support of the view that the freemartin 

 started as a female. 



The most important facts reported by Magnussen are those relating to the 

 histological condition of the testes of the freemartin. Well-developed testes 

 are present in some of the older freemartins, ranging in size from that of a 

 hazel-nut to that of a hen's egg. The vasa deferentia, the epididymus, and 

 notably even the tubular tissue characteristic of the testes were present, but 

 no germ-cells were found. Now the absence of germ-cells from the tubular 

 tissue of the testes of the adult freemartin may be accounted for, as Magnussen 

 does account for it, viz, as due to the "retention" of the testes of the free- 

 martin. This condition would not, however, be expected to hold for the 

 embrj^onic testes, where in the walls of the testes at birth one would expect 

 to find the germ-cells present. If a critical examination of these stages shows 

 that germ-cells fire not present in the tubules of the testes of the freemartin, 

 then the evidence from the freemartin shows not that the sex of the female 

 has been changed, but that under the influence of the blood of the male the 

 accessory organs, as well as the secondary sexual organs characteristic of the 

 male, have developed in the female; while at the same time her own female 

 accessory organs have correspondingly failed to develop fully. This state- 

 ment implies that the critical evidence for sex is the kind of germ-cell produced, 

 while the development of the secondary sexual characters and of the accessory 

 organs of reproduction in the mammal is determined, in part at least, by the 

 germ-cells. It will be recalled that, according to the most recent work in 

 mammalian embryology, the germ-cells originate in or from the region of the 

 intestinal tract, far removed from the final position in the gonad into which 

 they find their way by migration. If, then, it prove that no true germ-cells 

 are found in the testicular tubules of the freemartin, the presence of the 

 "testes," including even the epididymus, and tubules demonstrates only how far 

 the origin of these parts is dependent on something in the male ; but whether 

 this something comes from the germ-cells of the male (directly or indirectly) 

 or is a consequence of the genetic composition of the male is not shown. 



July 17, 1919, 



1 Tandler und Keller, 1911. Ueber das Verhalten des Chorions bei verschieden-geschlocht- 

 licher ZwillinRSgravitat des Rindes, uhd ueber die MorpholoRie des Genitales der weiblichen 

 Tiere, welche einer solchen Gravitat enstammen. Deutsche tieraerzliche Wochenschrift. 

 (No. 10.) 



^ Magnussen, H., 1918. Geschlechtslose Zwillinge. Eine gewohnlich Form von Herma- 

 phroditismus beim Rinde. Archiv. f. Anat. u. Physiol. Anat. Abt. 



