THE VASA EFFERENTIA. 487 



In the male the anterior segmental tubes, which even in the 

 embryo exhibit signs of atrophy, become in the adult completely 

 aborted (as has been already shewn by Semper), and remain as 

 irregular tubes closed at both ends, which for the most part do 

 not extend beyond the Wolffian duct (PI. 20, fig. 4, r. st.}. In 

 the adult, the first two or three segments with these aborted 

 tubes contain only accessory Malpighian bodies ; the remaining 

 segments, with aborted segmental tubes, both secondary and 

 primary Malpighian bodies. In neither case are the Malpighian 

 bodies connected with the aborted tubes. 



The Malpighian bodies in Scyllium present no special 

 peculiarities. The outer layer of their capsule is for the most 

 part formed of flattened cells ; but, between the opening of the 

 segmental tube and the efferent tubulus of the kidney, their cells 

 become columnar. Vide PI. 20, fig. 5. The convoluted tubuli 

 continuous with them are, I believe, ciliated in their proximal 

 section, but I have not made careful investigations with refer- 

 ence to their finer structure. Each segment is connected with 

 the Wolffian duct by a single tube at the hinder end of the 

 segment. In the kidney proper, these tubes become greatly 

 prolonged, and form the ureters. 



It has already been stated that the semen is carried by vasa 

 efferentia from the testes to the anterior segments of the Wolf- 

 fian body, and thence through the coils of the Wolffian body to 

 the Wolffian duct. The nature of the vasa will be discussed in 

 the embryological section of this chapter : I shall here confine 

 myself to a simple description of their anatomical relations. The 

 consideration of their connections naturally falls under three 

 heads: (i) the vasa efferentia passing from the testes to the 

 Wolffian body, (2) the mode in which these are connected with 

 the Wolffian body, and (3) with the testis. 



In PI. 20, fig. 4, drawn for me from nature by my friend 

 Mr Haddon, are shewn the vasa efferentia and their junctions 

 both with the testes and the kidney. This figure illustrates 

 better than any description the anatomy of the various parts. 

 Behind there are two simple vasa efferentia (v. c.} and in front 

 a complicated network of vasa, which might be regarded as 

 formed of either two or four main vessels. It will be shewn 

 in the sequel that it is really formed of four distinct vessels. 



