IX^ Mr. H. J. Carter on Microscopic Filaridae, 



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

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

 testinal sheath ; A, 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 Naidina; w, rectum; o, anus; ^, 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 l-540()th 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 ; 6, 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, cajcal 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. l-12th 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. 1 3. 



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. 



