100 Givynneth Biichanan : 



length of the first form, as nearly as could be computed, was 

 3.9 mm. ; that of the second, 3.6 mm : while the breadth of 

 both was .18 mm. 



I cut sections of the body wall of the earthworm in the 

 region of one of these patches, staining them with acetic acid 

 alum carmine, and in some cases double staining with eosin. 

 These sections showed a distinct fibrous capsule in the circular 

 muscle of the body wall of the host (Fig. 3, c). Inside this the 

 body of the jDarasite was cut across and surrounded by more 

 or less of the structureless substance before mentioned, which 

 was usually rather deeply pigmented (Fig. 3, p). This sub- 

 stance would seem to be either excrete material from the para- 

 site itself, or, rather, the disintegrated material of the body 

 wall of the host, as no cellular arrangement was made visible 

 by any method of treatment. The body of the parasite itself 

 had a very nematode-like appearance, but even under the low 

 power it was clear that its internal structure was not well pre- 

 served — a fact which was probably due to the presence of 

 cuticle, since the tissues of the host were in very good condi- 

 tion. Practically the whole of the internal cavity seemed filled 

 with long clear cells, which were apparently attached to the 

 alimentary canal at their inner end. Under a high power, how- 

 ever (4 eyepiece, 7 obj.. Fig. 4), these cells were found to be 

 lying loose in the body cavity attached at their outer end to 

 some inward j^rojections of the apparently structureless body 

 wall. This body cavity was divided fairly distinctly into two 

 halves, and each of these nuich less distinctly also into two. 

 In all four quarters were ten inward projections, but the 

 attached cells had none of the characteristic striations of nema- 

 todes. The only indication of the lateral line was very indis- 

 tinct. From it the clearest mesenteries (Fig. 4, mes.) pass to 

 the alimentary canal, along the whole length of which run two 

 structui-eless lines which stain homogeneously with eosin, in 

 much the same way as the body-wall, and, occasionally spread 

 almost round the alimentary canal. The cells of the latter are 

 very definite, and are regularly arranged with their nuclei to- 

 wards the inner cavity (Fig. 4, al.c). At one end is a curious 

 structure apparently arranged around the alimentary canal. 

 (Fig. 5.) On the outside is the homogeneously staining uuiss 



