644 
GILBERT E, JOHNSON. 
(i) I have not cut sections of the gut of Lumb. terres- 
tris to ascertain whether nematodes can be seen actually 
traversing the gut-wall, and I have no evidence on this 
question except the fact that on three occasions I have found 
species of larval nematodes alive among the soil contents of 
the gut. Whether the nematode is capable of making its 
way through the tissues of the gut-wall is not quite certain. 
The genus Rhabdit is is not provided, like some genera, with 
piercing mouth-parts, nor do the nematodes in a nephridium 
removed from a freshly killed worm appear at all capable of 
migrating through even its relatively thin wall. At the same 
time they must be able, to some extent, to push their way 
in among the tissues of the worm to be found imbedded in 
the muscular layer of the body-wall, as is sometimes the case. 
(ii) With regard to the other way of entrance, de Ribau- 
court, as already shown ( 11 , p. 297), has contributed definite 
evidence that nematodes can enter a worm by the coelomic 
pores. I have on one occasion seen larval nematodes 
apparently entering by the pores, and I have shown that the 
larvae can leave the worm by the same means. K. C. Schneider 
( 13 , p. 423) believes that the nematodes in the bladder of the 
nephridium have wandered in through the nephridiopore. 
It seems probable, therefore, that whether or not Rh. 
pellio in the natural state infects the worm through the 
gut-wall as well, it certainly does so by entering- through the 
dorsal pores, nephridiopores or reproductive apertures, or 
possibly by all of these. 
(7) Reason for the Presence of Rh. pellio in the 
Worm in Two Different Larval Conditions. — The 
jnost likely reason for the existence of two kinds of larvae — 
free and active in the nephridia and seminal vesicles, 
encysted and quiescent in the coelomic cavity — accords with 
the supposition that the nematodes enter the worm by the 
pores. 
(i) Firstly, those which pass in by the nephridiopores find 
themselves, as K. C. Schneider says, in the bladder-parts of 
the nephridia where they remain as the nephridial form. 
