9- THE REPRODUCTIVE SYSTEM 



95 



once more into separate threads. These then run out into a tangled complex 

 of fine filaments. The impression is thus created of a continuous net-like 

 layer at the base of the epithelium uniting the root-threads of separate cells. 

 A little farther forward the ciliated epithelium changes on the inside wall of 

 each spermduct to form a deep longitudinal furrow along whose base large 

 gland cells are exposed. Opposite this furrow, on the other wall of the sperm- 

 duct, there is a low longitudinal keel. A little farther forward again the furrow 

 broadens out into a longitudinal depression bounded at the sides by ridges 

 and similar ridges form on the opposite wall of the spermduct. The ridges 

 are peculiar structures : a rather dense tract of small cells without clear cell 

 boundaries lies within each ridge as a sort of syncytium, so that in transverse 

 section these tracts look like compact heaps of nuclei (Fig. 61). 



The middle part of the spermduct is distinguished by the very thick walls 

 and correspondingly narrow lumen (Fig. 60). The ciliary band remains, but 



mes 



Fig. 63. Transverse section of a male Lamellisabella zacksi a little behind the metameric part of the 



metasoma. 



cr - crypt in spermduct wall; cv - corpus cardiacum; ep - epidermis; gt - pyriform gland; 



mc - circular muscle layer; mes - mesentery; ml - longitudinal muscle layer; nd - dorsal nerve 



trunk; spd 3 - spermduct; vc - commissural vessel; vd - dorsal vessel; vv - ventral vessel. (After 



Ivanov, 1958a.) 



