THE VASA EFFERENTIA. 507 



Hodennetz in Verbindung. Dort nun wo diese letzteren sich an 

 den Nierenrandcanal ansetzen (Taf. XXI. Fig. 13 sg^ sg. 5 ) findet 

 sich jedesmal ein typisch ausgebildetes Malpig/u sc\\&s Korper- 

 chen, mit dem aber nun nicht mehr wie ursprunglich nur 2 Canale 

 verbunden sind (Taf. xxi. Fig. 14) sondern 3. Finer dieser 

 letzteren ist derjenige Ast des Nierenrandcanals welcher die Ver- 

 bindung mit dem nachst folgenden Segmentalgang zu besorgen 

 hat. An den Stellen aber wo sich an den Nierenrandcanal die 

 hinteren blind gegen den Hoden hin endenden Segmentalgange 

 ansetzen fehlen diese Matpigfo'schen Korperchen (Taf. xxi. Fig. 

 13 sgj] vollstandig. Audi bei Mustelus (Taf. XV. Figs. 8, 10) findet 

 genau dasselbe Verhaltniss statt; da aber hier nur 2 (oder 3) 

 Segmentalgange zu vasa efferentia umgewandelt werden, so 

 stehen hier am kurzen Randcanal der Niere auch nur 2 oder 3 

 Malpighi'sche. Korperchen. Diese aber sind typisch ausgebildet" 

 (Taf. xv. Fig. 10). 



From these two extracts it is clear that Semper regards both 

 the vasa efferentia, and central canal of the testis network, as 

 well as the longitudinal canal of the Wolffian body, as products 

 of the anterior segmental tubes. 



The appearance of these various parts in the fully grown 

 embryos or adults of such genera as Acanthias and Squatina 

 strongly favours this view, but Semper appears to have worked 

 out the development of these structures somewhat partially and. 

 by means of sections, a method not, in Scyllium at least, very 

 suitable for this particular investigation. I myself at first 

 unhesitatingly accepted Semper's views, and it was not till after 

 the study of the paper of Dr Spengel on the Amphibian kidney 

 that I came to have my doubts as to their accuracy. The 

 arrangement of the parts in most Amphibians is strikingly similar 

 to that in Elasmobranchs. From the testis come transverse 

 canals corresponding with my vasa efferentia ; these fall into a 

 longitudinal canal of the kidneys, from which again, as in Squatina 

 (PI. 20, fig. 8), Mustelus and Centrina, canals (the vasa efferentia 

 of Spengel) pass off to Malpighian bodies. So far there is no 

 difficulty, but Dr Spengel has made the extremely important 

 discovery, that in young Amphibians each Malpighian body 

 in the -region of the generative ducts, in addition to receiving 

 the vasa efferentia, is connected with a fully developed segmental 



332 



