180 JOHN LEWIS BREMER 



This paragraph by Fehx in the Keibel-Mall Hiiiiian Embiy- 

 ology' can hardly fail to arrest the attention of any one inter- 

 ested in the histological adaptation of cells and tissues to the 

 physiological function which they perform. The similarity 

 of the mesonephric glomeruli to those of the permanent kidney, 

 of the convoluted tul)ules and the collecting tubules in both 

 organs, the facts that develoi)mentally the excreting portions 

 of both organs are derived from the nephrogenic tissue and 

 have practically the same history, and that both Wolffian duct 

 and ureter open into the cloaca, all point so strongly to a sim- 

 ilarity^ of the function of the two organs that it would need over- 

 whelming proof to show that the product of the one gland is 

 not at least very like that of the other, in other words to show 

 that the meson ephros is not after all the 'middle kidney.' The 

 statement is little short of iconoclastic, for ever since the time of 

 Joh. Miiller and von Baer the Wolffian body has been known 

 as an excreting organ, continuing and gradually taking over the 

 work of the pronephros, functional in adult life in lower animals, 

 but replaced in turn in the higher orders by the permanent 

 kidney. Apparent proof of their activity is given by Nicolas, 

 who saw fine droplets of elaborated material in the epithelial 

 cells and in the lumen of the tubules, and more especially by 

 Bakounine, who after injections of sulphate of indigo into the 

 aorta or into the vitelline vessels of chick embryos found in the 

 epithelium of the Wolffian tubules the usual coloration given 

 by this dye in the kidney. 



A critical examination of Felix's argument shows that it is 

 based on a single fact, namely, that the mesonephros in man 

 degenerates and therefore ceases to function, before the kid- 

 ney is capable of activity, thus leaving the embryo without an 

 excretory oi-gan during a part of its existence. If during a part 

 of its existence excretion is not provided for and may therefore 

 be assumed to be unnecessary, why should it have been necessary 

 previously? If it is not necessary previously, then the meso- 

 ne]:)hros, apparently active previously, nuist have had some 

 other, as yet unknown function. 



' \(il. ■_', ]). S()S. 



