132 DR. J. STEPHENSON ON THE MORPHOLOGY, CLASSIFICATION, 



and stain a light pink ; the nuclei, 3-4 ^ in diameter, do not stain 

 deeply ; the cell contents are uniformly granular. Cell outlines 

 are present; the cells in the depth of the organ appear polygonal 

 in section, Avhile those nearer the mouth are elongated in the 

 clii-ection of the neck, and at the mouth these are continuous 

 with the surface epithelium. It may be that all the cells of the 

 interior reach the surface. 



The figure of one of these organs shows a remarkable similarity 

 to a simple type of spermatheca ; and it does not seem impossible 

 that spermatheca? may have arisen from such structures. 



(8) liudimentary {i.e., Incijyient) Gizzards. 



Invisible in dissection, but revealed in the microscopic examina- 

 tion of sections, is an incipient gizzard belonging to segm. xi 

 (fig. 4, rud.), and, more rudimentary still, one in x. IS^otable is 

 the thickening of the connective- tissue layer in the incipient 

 gizzards, outside the layer of the strengthened circular muscular 

 fibres. 



(For references to literature see end of next article.) 



Explanation of Plate I. 



Fig. 1. Nepliridium of Draivida japonioa, X70. coil, spiral coil; d., duct; 

 ej>., epithelial lining of sac ; loop, twisted loop ; )»,., muscular coat of sac ; 

 n., ueplirostoine ; n. c, nephrostomial canal; p., peritoneal coat of sac; 

 sac, oval .sac ; spin., spindle-shaped portion ; tr., trunipet-sliaped expan- 

 sion of duct at junction with body- wall. 

 Fig. 2. Section through portion of testis sac, XlOO. h.v., blood-vessels; c, cells in 

 sac; ep., epithelial lining of sac; ./., elongated epithelium of funnel; 

 ^., pink-staining ground-substance of sac contents; m., muscular fibres; 

 n., nuclei in ground-substance ; sept., septum 9 10 ; p., peritoneal coat of 

 sac ; t., testis; v. def., vas deferens; .r., yellow or brovi'n chloragogen-like 

 grains and masses. 



Fig. 3. Section of prostate, somewhat oblique, XoO. The covering layer of flattened 

 peritoneal cells, if and where present, is not to be seen at this magnifica- 

 tion, atr., atrium in centre of prostatic cells, with epithelial and 

 muscular coats; nuc, nuclei of prostatic cbWa ; prost., prostatic cells; 

 V. def., vas deferens in wall of atrium ; x., vacuoles with central particle. 



Fig. 4. Longitudinal section, rather oblique, through ovarian chamber and neigh- 

 bouring segments (semi-diagrammatic), X 20. ann., annular chamber 

 round gut ; d.v., dorsal vessel ; ep., epithelium of ossophagus ; f., female 

 funnel; giz., muscular thickening of ojsophageal wall, constituting the 

 gizzard of segm. xii ; par., parietes, with epithelial, circular, and longi- 

 tudinal muscular layers; o.c, ovarian chamber; rud., rudimentary 

 gizzard of segm. xi; sac, ovisacs; 10/11, 11/12, 12/13, the corresponding 

 septa. 



Fig. 5. Section of accessory (copnlatory) gland, X50. c, cells filling up interior 

 of gland; c.?»., circular muscular fibres of body- wall; cm.', two strands 

 of circular muscle traversing plug of cells at mouth of gland ; ep., surface 

 epithelium ; m., muscular coat of gland (the peritoneal coat not visible at 

 • this magnification) ; sept., septum 9/10; t., trabecular (blue-staining) 

 connective tissue, the longitudinal muscular layer of the body-wall being- 

 absent here. 



Fig. 6. Transverse section through ovarian chamber (semi-diagrammatic), X12. 

 ctlim., alimentary canal ; ami., annular chamber round gut; d.v., dorsal 

 vessel ; o.c, ovarian chamber ; ova, masses of ova, cut tangentially to 

 attachment of ovary to anterior wall of chamber ; par., parietes ; x., upper 

 limit of ovarian chamber; v.ch., ventral chamber; v.n.c, ventral nerve 

 cord ; V.V., ventral vessel ; y., j'olk masses. 



