64 W. BALDWIN SPENCEE. 



through the plane F. On the left side, which lies slightly in front of the 

 right, the union of vas deferens and ejaculatory duct is cut through, and on 

 the right the termination of the vesicula seminalis of that side and the 

 proximal end of the ejaculatory duct. Dorsally the vesiculse seminales are 

 still connected with a common median portion which contains on its roof a 

 ridge pierced by two small tubes leading from the common chamber of the 

 vesiculse into the testis. The glandular nature of the walls of the vesicular is 

 seen. Outline drawn with camera, Zeiss, A*, details with C, oc. 2. 



Fig. 18 (cf. Section F). — Transverse section across the body of a very 

 small young male through the plane F. This section is drawn to show that 

 in the young stages there is no doubt that the vesiculae pass right through 

 the substance of the hook-gland, though in the adult form the other part 

 becomes so thin by pressure that the tubes appear to encircle the glands. 

 Drawn with the camera, Zeiss, A, oc. 2. 



Fig. 19 (cf. Section G). — Transverse section across the body of a male 

 through the plane G, On each side, owing to the bending upon itself of the 

 vesicula seminalis, this is cut in section in two parts. The vesiculae arc full 

 of ripe spermatozoa. Ventrally the two ejaculatory ducts are cut through, 

 and dorsally the median testis, which is somewhat pinched in between the 

 vesiculse and hook-glands. Outline with camera, Zeiss, A* details with 

 C, oc. 2. 



Fig. 20 (cf. Section H).— Transverse section across the body of a male 

 through the plane H. This lies behind the region of the vesiculae, but on the 

 ventral surface the ejaculatory ducts are cut through, and dorsally the testis. 

 The mesenteries passing from the walls of the raid-gut to the hook-glands, 

 and on from these to the body-wall, are distinctly seen. Outline with camera, 

 Zeiss, A*, details with C, oc. 2. 



Fig. 21 (cf. Section I). — Transverse section across the body of a male 

 through the plane I. Of the reproductive organs only the testis is present, 

 and its walls are here made up of a thick layer of protoplasm with nuclei, but 

 with no distinct cell outlines. The section shows that the testis extends 

 beyond the region of the hook-glands, the mesenteries of which serve now 

 simply for the sujjport of the wall of the alimentary canal. Drawn with 

 Zeiss, C, oc. 2. 



Fig. 22. — Transverse seei.ion across the body of a female which is not fully 

 mature (i. e. the uterus contains no embryos). The section passes through 

 the spermatheca on each side, and beneath these lies the uterus cut in section 

 posteriorly to its union with the oviducts and s|)ermathccal ducts. The two 

 oviducts are cut through as, one on either side, they pass through the middle 

 of the hook-gland. The section lies immediately in front of the anterior 

 extremity of the ovary. Outline drawn with camera, Zeiss, A*, details 

 with C, oc. 2. 



Fig. 23. — Transverse section across the middle of the body of a young 



