34 WRIGHT AND MACALLUM. [Vol. I. 



shapes are due to amoeboid movements; but the facts cited 

 in the following paragraphs seem to show that it is brought 

 about by functional waste and decay. 



The observations of Sommer on Distomum hepaticum and 

 Kerbert on Dist. Westermanni tend to show that digestion in 

 these forms is intracellular. The intestinal cells in the first 

 named Trematode seem to throw out processes which draw in 

 the particles of food into the interior of the cells. 



This may be the case in the forms mentioned, but intracellular 

 digestion plays at the most only a subordinate r61e in Sphyra- 

 nura. 



The food of Sphyranura consists almost wholly of structures 

 derived from the epithelium and blood of Necturus. Cells from 

 all the layers of the cutaneous epithelium of the host are present 

 in the intestinal contents, and with the cells of the basal epi- 

 thelial layer are swallowed those wandering cells or leucocytes 

 quite common amongst the latter, more especially when inflam- 

 mation of the subjacent tissues is induced by the irritation of 

 the parasite. All these cells can be observed in a healthy 

 vigorous specimen of the Sphyranura. Besides these formed 

 elements there are an immense number of granules, consisting 

 principally of the disintegrated remains of the cells of the host. 

 Many of these granules, and all the larger ones, have, after 

 treatment with the chrom-osmio-acetic mixture and staining with 

 alum-cochineal, a vivid stain, and they are, therefore, the chro- 

 matin elements of the nuclei of the swallowed cells. The 

 larger granules have characteristic shapes, sometimes round, 

 sometimes crescent-shaped, and at other times they manifest 

 that peculiar shape so common in the nuclei of the wandering 

 cells of Necturus. All the stages of the disintegration of the 

 cells can be fully seen, which give rise to these chromatin 

 bodies as the ultimate visible product. First, the cytoplasma 

 disappears gradually, leaving the nucleus intact; then the 

 nuclear membrane breaks down, followed by the solution of 

 the nuclear net-work, setting free the chromatin elements. In 

 those cases where the nuclei are observed free and intact one is 

 surprised to find the chromatin in them appear clear and brill- 

 iant, while the caryoplasma is not visible when treated with 

 Flemming's fluid and stained. The reason for this is not far to 

 seek ; it is well known that the chromatin will dissolve and dis- 



