NEMATOMORPHA ANATOMY 



167 



is found in the larva, though- the two dorsal splits from the walls 

 of which the spermatozoa will arise are present. They are lined by 

 a definite epithelium (Fig. 83), and this serves at once to distin- 

 guish them from the body-cavity. Posteriorly the splits narrow 

 and become the two vasa deferentia which open one on each side 

 into the cloaca. The cells 

 lining the lumen give rise to 

 secondary cells, and these be- 

 come spermatozoa, the process 

 extending from behind for- 

 wards. The external organs 

 bursa, etc described by 

 Vejdovsky were not found 

 by von Linstow. 



In the female larva two 

 similar splits are present ; 

 these form the egg-sacs. Pos- 

 teriorly they end in two short 

 oviducts which open into a 

 uterus, in which fertilisation takes place, and in which the secre- 

 tion arises which cements the eggs together. In the adult the 

 ovaries and a receptaculum seminis are found, in addition to the 



organs present in the 

 9* % larva. The ovaries 



are formed from 

 modifications of the 

 packing tissue ; they 

 begin close behind 

 the head, and soon 

 attain such dimen- 

 sions as to compress 

 the egg -sacs and 

 body-cavity to small 



-Section through a female Gordius tolosanus silts. Alter a time 



the wall between the 



Fig. 85. Section through a mature female 

 Gordius tolosanus. (From von Linstow.) 

 Lettering as in Fig. 84 ; g, egg-sac ; k, ovary. 



Fig. 



when the deposition of ova is almost complete, a, b, c, 

 d, e, and /, as in Fig. 84 ; g, egg -sac ; h, ovary 

 almost empty ; i, dorsal canal containing eggs ; j, re- 

 ceptaculum seminis. 



sorbed, and the eggs 



into the latter. 



ovary and the egg- 

 sacs becomes ab- 

 In the old females. 



where the egg sacs are empty, there is a considerable space round 

 the exhausted ovary, into which eggs continue to fall off; there 



