150 



stain at all. In reality, these apparent regions are not distinct, the 

 gland cells being continuous from the periphery of the gland to the 

 lumen, with no interruption by the muscle band, as will be shown in 

 the next paragraph. 



The muscle elements in the spermathecal duct exhibit an interest- 

 ing peculiarity in arrangement and derivation. At the ectal end of 

 the ampulla the well-developed circular muscle-layer instead of con- 

 tinuing over the duct unchanged becomes converted into a series of 

 muscle bands which extend at right angles to the direction taken by 

 the fibers of the same layer on the ampulla. These bands do not form 

 a continuous layer but occur at intervals, thus forming a cylinder of 

 muscle bands, each of which is separated from the neighboring ones 

 by spaces through which extend the prolongations of the gland cells 

 to meet the lumen. These muscle bands continue through to the ex- 

 ternal hypodermis and become allied with the circular muscle layer 

 of the body wall. Each band appears to be composed of two similar 

 parts closely approximated, and in all cases this double condition of 

 the bands seems to be constant. 



Ventral Glands. — The peculiar and problematical organs which 

 have been given several names ("Kopulationsdriisen" of Michaelsen 

 and Ude, ''copulatory glands" and "outgrowths of the ventral nerve 

 cord" of Beddard, ''ventral glands" of Eisen) are present in speci- 

 mens of this species. They are moderately developed (F\. IX, Fig. 

 20) and are closely and uniformly associated with the ventral nerve 

 cord in XIII and XR^. They almost completely surround the ventral 

 ganglia, leaving only a small free space on the dorsal median line 

 of the nerve trunk. In transverse section (PI. IX, Figs. 18, 19) they 

 appear to be made up of a mass of distinctly nucleated spindle-shaped 

 gland cells which lie parallel to each other and extend ventrad. They 

 do not have the lateral wing-like developments which are present in 

 some species, but are compact and bulbous in appearance. Each pene- 

 trates the body wall in the mid-ventral region immediately under the 

 nerve cord, thus opening to the exterior. In the majority of the speci- 

 mens examined these glands are not bilaterally symmetrical but one 

 side is more strikingly developed than the other, giving the whole the 

 appearance of being turned over to one side. In all of the specimens 

 examined the greatest development uniformly occurred on the same 

 side in both glands, but in some individuals it was found on the left 

 side, while in others it was on the right. The two glands differ but 

 little in size but there is a difference in shape. The ental ends of the 

 gland in XIII extend above the level of the ventral ganglion, forming 

 a mid-dorsal fossa, while the ental ends of the one in XIV do not 

 thus extend, and a fossa is not formed. 



