444 MR. J. B. SUTTON ON HYPIiUTROl'HY. [May 5, 



stoma cysticolum the female has rudiments of testes, but no male 

 generative aperture. 



In those forms in which the individuals inhabiting one cyst are 

 not different in appearance, the sexual organs have a different struc- 

 ture ; each individual is here androgynous, but differs from the free 

 living androgynous species in that the testis is developed only on 

 one side of the body, and there is but one generative aperture. In 

 Myzostoma pentacrinus, however, there are small remnants of the 

 other testis, but no second male aperture. The testis also, as in the 

 dioecious forms, is a small compact gland. Since the testes of the 

 dwarf males are fully developed on both sides, we must not regard 

 the herma[)hrodite species M. pentacriiii and M. defonnatum as tran- 

 sitional between the typical hermaphrodite forms and those that are 

 dioecious, but the latter must be derived independently from living 

 forms. 



In M. cysticolum the male and female are found associated in a 

 common cyst, and increasing in size with the growth of the cyst 

 perforate the arm-joints of their host together. The growth of 

 the cyst is, of course, caused by the presence of the parasite ; the 

 female deposits her eggs within the cyst, and the young em- 

 bryos, after they have abandoned the cyst and lost their ciliated 

 coat, associate togetlier in pairs, and bore their way through the 

 arm-joints. In both the sexual development begins with the 

 appearance of testes ; but in the female the testes disappear entirely, 

 or leave but a minute rudiment, when the ovaries make their appear- 

 ance in addition '. 



Among the most striking examples of the peculiar value of hyper- 

 trophy in this direction must be mentioned tlie curious malformed 

 generative organs which occur in the cattle known as " Free-martins." 

 Hunter was one of the first to carefully investigate ihe condition of 

 the reproductive organs in these cases ; and the valuable dissections 

 he made, now in ^the Hunterian Museum, are striking monuments 

 of his inquisitiveness in this matter. 



Stock-breeders hold the opinion that when a cow produces twins, 

 one a male and the other a female, the latter is uiij)roductive (im- 

 perfect). This is very frequently true, but by no means always so. 

 An imperfect calf under these conditions is known as a Free-martin 

 or Martin-heifer. Careful comparison of the detailed descriptions 

 of the dissections of these malformations, and similar cases in Sheep 

 and Goats which have come under my observation, show most 

 conclusively that in these cases we have to deal, not with any one 

 malformation common to all examples of Free-martins, but rather 

 with instances in which both sets of organs have attenjpted to attain a 

 functional condition, with tlie result that both have failed to reach it. 

 In some of these cases the Wolffian ducts iiave advanced many stages 

 towards making a fairly complete set of efferent ducts for the testicles, 

 and the calf approaches somewhat to a bull-calf. In other 

 instances the Miillerian ducts have made greatest progress, and a 



1 I am indebted to Mr. F. Beddard for drawing my attention to these inter- 

 esting observations of Dr. von Graff. 



