88 ANATOMY OF THE ENOPLA. 



than one globule on these thread-like organisms, and the comparative steadiness of the body of 

 the spermatozoon, contrasted with the lashing of the tail, might have raised a doubt in the mind 

 of the distinguished author. The spermatozoa in Tetrastemma vermicula (Plate XVI, fig. 6), 

 though minute, are amongst the most active of the group. They are slender at one end, and 

 gently dilate towards the opposite, which is furnished with a very long tail. Just in front of the 

 posterior extremity is in certain views a somewhat abrupt swelling of the body, as if from 

 an adherent globule, but none were observed without the enlargement. The spermatozoa of 

 A. pulcker (Plate XVII, fig. 10) have bodies more or less dilated at one end, and tapered towards 

 the attachment of the tail, but in other views they are spindle-shaped. They are very minute, 

 even more so in the specimens examined than in the smaller Enopla. In Tetrastemma Bobertiance 

 these bodies present the form of slender rods, having a small globule attached near the end 

 (Plate XVII, fig. 26) furnished with the tail. After remaining in the water a short time, the 

 form of the spermatozoon completely changes, the rod or body becoming fused into the globule, 

 which enlarges accordingly, and assumes the form of a granular cell with the filiform tail still 

 adherent. A granular aspect was likewise observed in many of the newly voided spermatozoa of 

 Ampkiporus bioculatus, the bodies in this case being ovoid and somewhat pointed at the ends 

 (Plate XVII, fig. 25). 



b. Female Organs. 



In the matured females of Amphiporus lactifloreus the ova extend from the oesophagus almost 

 to the tip of the tail, each ovary containing from one to seven ova, which, when fully developed, 

 are seen with the naked eye through the attenuated parietes of the body. They attain a com- 

 paratively large size before deposition, and are not much less in small specimens, though 

 few in number. The female in the ripe state has a greyish- white appearance, with the dorsal tube 

 for the proboscis extending nearly from end to end, though its diameter is diminished posteriorly 

 from the encroachments of the ovaries. In the smaller species the arrangement of the system can 

 readily be observed in the living animal as a transparent preparation (Plate XVI, fig. 13). The 

 outer hyaline investment of the egg is generally corrugated before extrusion. 



M. Duges correctly located the generative products in pyriform pouches along the sides of 

 the body, and thought they resembled the ovaries of Tcenia, which open exteriorly in every 

 segment. He observed three or four vesicles containing a pulpy substance in Pros- 

 toma lumbricoides, so that in all probability his specimen was a female. M. de Quatrefages, 

 Prey and Leuckart, and Dr. Johnston, again, describe the ova as occurring in a free condition 

 between the body-wall and the alimentary cavity. The former (M. de Quatrefages) confounds 

 the digestive with the generative system, indeed, gives a tolerable figure of a cell from the wall of 

 the alimentary cavity as one of the true stages in the growth of the spermatozoa ; and again refers 

 {' Voyage en Sicilie/ Plate XXII, fig. 2) to the glandular wall of the said cavity as representing 

 generative caeca. The spermatozoa, therefore, which he shows, had either been discharged 

 externally, or procured from a specimen in such a condition as to leave no room for doubt. His 

 figure of the male elements from N. balmea is incorrect, for the body of each is too short and 

 thick. He considers that it is only after the granular corpuscles fall out of the caeca into the 

 lateral cavities that they assume their special characteristics as sperm-cells. He thus fails to 



