72 ADAM SEDGWICK. 



Malpigblan body, the structure developed independently 

 in the intermediate cell mass certainly giving rise to more 

 than the Malpighian body. 



I now pass to the development of the secondary tubules, 

 &c. Fiirbringer^ derives them also from peritoneal in- 

 growths. He has not, however, given, so far as I know, any 

 figures showing this. I have examined this point with 

 some care, but have quite failed to discover any traces of 

 these secondary ingrowths. 



The secondary tubules appear to me to arise from small 

 masses of cells, which occupy, at a slightly earlier stage, the 

 position of wt.^ in fig. 11. In this figure the vesicular 

 rudiment of a secondary tubule has appeared in this mass of 

 cells. The tertiary and quaternary, &c., tubules appear to 

 arise successively at a slightly later stage from similar 

 small masses of cells, which are always placed just dorsal to 

 the last-formed tubule. The later development of these 

 secondary, tertiary, &c., Wolffian tubules is very similar to 

 that of the primary. 



The time of development of the primary tubules relatively 

 to that of the secondary, &c., tubules varies in different parts. 

 Anteriorly the primary tubule is much more developed (in 

 fact, has acquired an opening into the Wolffian duct), before 

 the first trace of the secondary tubule arises, than posteriorly, 

 where a secondary and tertiary tubule have appeared almost 

 before the primary tubule has lost its vesicular structure 

 (fig. 13). 



The development of the secondary, &c., Wolffian tubules in 

 the chick appears to be very much abbreviated. 



Whatever may have been their development in phylogeny, 

 no light is thrown upon it by their ontogeny. Nor even can 

 a comparison be made between their development in the 

 chick, and that in other forms in which it is possible to 

 suppose the development is less abbreviated. In Elasmo- 

 branchs the secondary tubules, as Balfour^ has shown, 

 develop in connection with the Malpighian bodies of the 

 primary tubules, as outgrowths from them, which eventually 

 open into the collecting tubules of the segment in front. 

 Neither Balfour nor, as far as I know, any other observer, 

 have elucidated the development of the tertiary, &c., tubules 

 in Elasmobranchs. 



In the Salamander Fiirbringer^ has shown that they 

 develop as they do in the chick from cell masses closely 



^ Loc. cit. 



' Balfour, ' Elasmobranch Fishes.' 



' Loc. cit. 



