126 PROCEEDINGS OF THE ACADEMY OF [Feb., 



canal to form a plexus is found in the median portion of the nephridium 

 of the leech (Graf. 1898), and also in the Enchytrmcke (Bolsius, 1892) 

 and the Discodrilidce (Moore, 1897). Certain nephridia of some mem- 

 bers of the Naidomorpha, Lumbriculidce (Vejdovsky, 1884), and Tubi- 

 ficidcc (Stole, 1888) possess on that part of the nephridium just follow- 

 ing the funnel an oval swelling of a brown color, and within which the 

 nephridial lumen forms a network. In the case of Nais, however, this 

 swelling appears to consist of but a single cell. 



Shearer (1906) has recently made a detailed study of the nephridia 

 of D. tceniatus. He finds that in their general form and arrangement 

 they correspond to the description given by Harmer (1889a). He 

 adds, however, the important fact that the inner end of each nephrid- 

 ium bears a large number of the curious structures discovered by 

 Goodrich, and called by him "solenocytes" (1898). The cilia of the 

 solenocytes traverse the length of the nephridium, giving it the ap- 

 pearance of being lined with cilia. As to the presence or absence of 

 these structures in the posterior four pairs of nephridia of D. conklini, 

 I am not able to decide with the material at hand. It seems, however, 

 quite certain that solenocytes are not present in the nephridia of the 

 first pair. Here the images afforded by my material are quite clear, 

 the finer structure in the most favorable instances being quite well 

 preserved, and affording a good basis for decision. If present at all 

 the solenocytes should be found cephalad of what I have termed the 

 ''anterior canal," and within the strand of protoplasm in which this 

 canal runs (see fig. 26a and text fig. IV). This portion of the pro- 

 toplasmic strand, however, appears uniform in structure, and con- 

 tains nothing which would indicate the presence of solenocytes. 



Amoeboid Cells. — In many series of sections there appear large cells 

 of irregular form, situated in the cavity of the head and in the body 

 cavity of the neck region, dorsad and laterad to the anterior portion 

 of the oesophagus (figs. 3 and 4, am.c). Their cytoplasm is coarsely 

 granular in appearance, and is frequently seen to contain densely 

 staining inclusions of various shapes and frequently of large size. 

 The nuclei of these cells are vesicular and contain but little chromatin, 

 outside of the large spherical karyosome. In at least one instance a 

 number of these cells were found in an evident state of degeneration, 

 some within the cavity of the head, others buried in its ventral hypoder- 

 mis. This latter circumstance, together with the varying location 

 of these cells within the limits indicated, and the fact that their 

 shape conforms to the outline of the adjacent tissues, strongly indicates 

 that their nature is amoeboid. Their origin is obscure; but their close 



