STRUCTURE AND DEVELOPMENT OF VERTEBRATE OVARY. 421 



length in his valuable memoir on their urogenital sjstemJ Ac- 

 cording to Braun the segmental cords in Reptilia are buds from 

 the outer walls of the Malpighian bodies. The bud from each 

 Malpighian body grows into the genital ridge before the period 

 of sexual differentiation, and sends out processes backwards 

 and forwards, which unite with the buds from the other Mal- 

 pighian bodies. There is thus formed a kind of trabecular 

 work of tissue in the stroma of the ovary, which in the Lacertilia 

 comes into connection with the germinal epithelium in both 

 sexes, but in Ophidia in the male only. In the female, in all 

 cases, it gradually atrophies and finally vanishes, but in the 

 male there pass into it the primitive ova, and it eventually 

 forms, with the enclosed primitive ova, the tubuli seminiferi. 

 From my own observations in Eeptilia I can fully confirm 

 Braun's statements as to the entrance of the primitive ova into 

 this tissue in the male, and the conversion of it into the tubuli 

 seminiferi. The chief difference between Eeptilia and Mam- 

 malia, in reference to this tissue, appears to be that in 

 Mammalia it arises only from a few of the Malpighian bodies 

 at the anterior extremity of the ovary, but in Eeptilia from all 

 the Malpighian bodies adjoining the genital ridge. More 

 extended observations on Mammalia will perhaps show that even 

 this difference does not hold good. 



It is hardly to be supposed that this tissue, which is so con- 

 spicuous in all young ovaries, has not been noticed before ; but the 

 notices of it are not so numerous as I should have anticipated. 

 His' states that the parenchyna of the sexual glands undoubtedly 

 arises from tlie Wolffian canals, and adds that while the cortical 

 layer (Hulle) represents the earlier covering of a part of the 

 Wolffian body, the stroma of the hilus, with its vessels, arises 

 from a Malpighian body. In spite of these statements of His, I 

 still doubt very much whether he has really observed either the 

 tissue I allude to or its mode of development. In any case he 

 gives no recognisable description on' figure of it. 



Waldeyer^ notices this tissue in the dog, cat, and calf. 

 The following is a free translation of what he says, (p. 141) : 

 — " In a full grown but young dog, with numerous ripe 

 follicles, there were present in the vascular zone of the ovary 

 numerous branched elongated small columns (Schlauche) of 

 epithelial cells, between which ran blood-vessels. They were 

 only separated from the egg columns of the cortical layer by a 

 row of large follicles. There can be no doubt that we have 

 here remains of the sexual part of the Wolffian body — the canals 



^^'Arbeiten a. d. Zool. Zoot.,' Iiistitut. Wurzburg, Bd. iv. 



' Aixhiv f. mikros. Auat.,' vol. i, p. 160. 

 ' Loc. cit. 



