i8 



II., fig. 5, shows the mature male in its relative size to the mature 

 female, fig. 4. Fig. 6 shows the posterior end more enlarged with the 

 spicule (q), anus (y), bursa (z), and the testis (t). At this stage 

 copulation takes place, the male and female being about equal in 

 size, having a length of .8mm. (yL of an inch) the male being mature, 

 but the female not yet fully developed. The male clasps the body 

 of the female (PI. I., fig. 18) by means of the bursa so that the open- 

 ing of the testis is directly in contact with that of the ovary, and 

 discharges its spermatoza into the small cavity which is situated just 

 under the opening. The male has now completed its life and dies, 

 while the female goes on to develop eggs and young. The body 

 continues to increase in length and still more in diameter, assuming a 

 somewhat distended, cigar shaped form (PL 11. , fig. i). The eggs in 

 the ovary begin to mature, those nearest the opening first, and soon 

 the worm reaches the stage shown at fig. 2. The intestine is no lon- 

 ger the most prominent organ of the body cavity. That is now 

 almost filled by the ovary, a long wide tube extending from the 

 oesophagus to the posterior end of the body, filled with eggs in all 

 stages of development. Soon the young begin to hatch and move 

 about in the ovary, whence they are forcibly discharged through the 

 side opening. In adult worms which were killed during examination 

 the eggs continued to hatch but the young worms seemed unable to 

 reach the exterior. They squirmed vigorously about, travelling 

 from end to end of the body cavity (which finally became nothing 

 but a sack, full of a living mass of young worms) and occasionally 

 one would chance upon the vulva and protrude its head, but they 

 always drew back again before getting out completely and showed by 

 their actions that the forcible discharge by the parent which was 

 observed in living specimens was necessary for their release. Fig. 

 3 shows a living mature female, and fig. 4 one which was dead and 

 somewhat disorganized. 



Plate IX., figs. 4 and 5 shows the male and female of another species 

 in which the eggs are discharged when partially developed. Fig. 1 

 is a small male of another related species. In this is shown at (<?) a 

 small opening through the body wall just opposite the oesophagal 

 bulb, which is the orifice of an excretory organ, a long tube running 

 down the body which occurs in most nematodes but is not easily 

 distinguishable. Fig. 2 shows the posterior end of this male 

 more enlarged, bursa (z), spicule (q), intestine (o), and testis (t). 



