114 Mr. H.J. Carter on Miwoscopic Filaridae. 



d, buccal dilatation of oesophagus ; e, oesophagus ; /, muscular 

 sheath of ditto ; g, peritoneal sheath of ditto reflected on to in- 

 testinal sheath ; h, point of union of oesophagus and intestine ; 

 i, intestine ; k, hepatic organ covered by intestinal sheath ; 

 I, posterior portion ; m, posterior end of intestine, uncovered by 

 hepatic organ, but presenting on its surface scattered groups of 

 vesicles, apparently in cells like the biliary cells covering the in- 

 testine of the Na'idina ; n, rectum ; o, anus ; p, seminal duct ; 

 q, penis, exsertile at the anus ; r, muscles connected with the 

 penis. 



Fig. 12. Horny elements of the penis separate, showing their scaphoid 

 form. 



Fig. 13. Half the female organs of generation, proportionally magnified 

 (scale about l-12th to 1 -5400th of an inch) : a, ovary, containing 

 the ova in their first stage of development, that is, consisting of 

 a cell-wall lined with transparent endoplasm, bearing in one part 

 the nucleus, which afterwards becomes the germinal spot and 

 vesicle ; b, ova more advanced, each occupying an entire seg- 

 ment of the ovisac, the endoplasm becoming opake by the deve- 

 lopment of the yelk-granules ; c, unimpregnated ovum ready to 

 pass into the oviduct ; d, caecal end of the ovisac, containing the 

 granular matter supposed to be the remains of the spermatopho- 

 rous cells after the spermatozoa have left them to penetrate the 

 ovum; e, oviduct; /, point of junction of, with the ovisac ; 

 g, i, dilated portion filled with spermatophorous cells and their 

 included spermatozoa ; h, constricted portion of oviduct ; i, trun- 

 cated portion of ditto; k, a few of the spermatophorous cells 

 separate ; I, impregnated ovum, now without the germinal ve- 

 sicle, but surrounded by an additional coat, viz. the shell or cho- 

 rion, ready for segmentation. 



Fig. 14. Half the male organs of generation, greatly magnified: a, testis, 

 or end of the spermatic sac, which throws off from its surface 

 the spermatic cells, each of which here consists of a cell-wall 

 lined with transparent endoplasm bearing in one part the nu- 

 cleus ; b, portion of the spermatic sac where the endoplasm has 

 developed granules or nuclei, which become the spermatophorous 

 or daughter cells ; c, portion where the nuclei have become elon- 

 gated and their proper cells become evident, while they have 

 also assumed a radiated arrangement ; d, last portion, where the 

 nuclei, now transformed into spermatozoa, but still within the 

 daughter cells, have left the parent ; e, constricted portion of 

 • spermatic sac going to form with its fellow (/) the seminal duct ; 



g, seminal duct, truncated ; h, spermatophorous cells. 



N.B. The following figures, which are delineated after nature, 

 have all been drawn on the same scale, viz. 1-1 2th to 1 -5400th 

 of an inch, in order that their relative proportions might be pre- 

 served for the purpose of illustrating the development of the 

 spermatozoa. 



Fig. 15. Spermatic cells increasing from a mere point to the full size of 

 their first stage, which consists of a cell-wall lined with endo- 

 plasm and bearing in one part a nucleus : this corresponds with 

 part a, fig. 13. 



Fig. 16. Shows the first appearance and gradual increase in size of the 

 nuclear points and daughter cells in the endoplasm of the sperma- 

 tic cell, from which the spermatozoa are ultimately developed. 



