A. M. Taylor 271 



which the spicules are attached, but the actual relations I have not 

 been able to determine. 



The body cavity, which in nematodes is probably not a true coelom, 

 extends from end to end of the animal and can easily be made out in 

 optica] section. I have not been able to see any corpuscles or other 

 bodies floating in it. There are no cilia. The alimentary canal and 

 reproduction organs hang freely in the cavity unattached by any 

 mesentery, and connected only near their openings and by a few 

 muscular strands in the case of the former organ at the anterior end 

 (PI. Ill, figs. 5 and 6). 



Reproduction organs. The sexes are separate. 



The male organs consist of the reproduction gland, its duct and 

 certain accessory cuticular organs already mentioned in the description 

 of the whole animal. The reproduction gland is a simple elongated 

 organ, the posterior end of which is tubular. This tube opens into 

 the cloacal depression near its anterior margin. The anterior end of 

 the organ which is solid and may be called a testis projects freely forward 

 to a point about three-fifths the distance from the mouth to the anus. 

 It lies usually upon the right side of the alimentary canal. 



At the extreme anterior end two kinds of cells can be distinguished, 

 smaller laterally placed cells which are probably follicular (PI. Ill, fig. 6) 

 and larger more centrally placed cells which are spermatogonia. In 

 tracing the reproduction gland backwards towards its tubular posterior 

 continuation one can follow the development of the spermatogonia 

 into the resting or growth stage of spermatocyte I. These are 

 very large cells each of which occupies the full width of a follicle. 

 Each contains one large nucleus in the resting phase. Then comes 

 a series of smaller cells which are no doubt the products of the division 

 of spermatocyte I and so may be called spermatocyte II. They no 

 longer shew a resting nucleus but chromatin grains can be seen indis- 

 tinctly. The difficulty of staining has prevented the determination 

 of the details of the meiotic phase which no doubt occurs here. The 

 subsecjuent division of spermatocytes II into spermatids is not dis- 

 tinguishable ; but the lowest cells in the tube are almost certainly 

 spermatids. If this is the correct interpretation, then the di\'ision of the 

 chromosomes of spermatocyte II follows the meiotic stage immediately 

 without any intervening resting stage, as no distinct nucleus can be 

 seen after the growth period of spermatocyte I. 



The final formation of the spermatozoon (which is non-flagellate) 

 takes place at the posterior end, and the nearly mature sex cells are 



18—3 



