No. I.J SPHYRANURA OSLERI. 33 



The epithelial layer is sometimes 60 ^i in thickness, at other 

 times it is found as thin as 3.5 ^t, while the breadth of each cell 

 in this layer does not vary much, being about 20 ^. The 

 nuclei are oval or flattened in the thinner epithelial layer, 

 rounded in other conditions, and measuring less than 11^. 

 The shapes of the free ends of the cells are different even in the 

 same section, being wedge-like, flattened, or rounded. The 

 nucleus is usually at the base or fixed end of the cell, con- 

 tains several chromatin bodies, and a distinct reticulum. The 

 cytoplasma is granular, but in some preparations, notably 

 those made with Flemming's fluid, a delicate reticulum is 

 observable with trabeculae stretching tov/ard the free surface of the 

 cell. (Fig. II.) The basal border has a serrated appearance, 

 probably due to the presence of the so-called prickles. The 

 free border of the cell is usually covered with a layer of gran- 

 ules, this layer exhibiting a fine striation, which may be due to 

 the presence of permanent cilia or to amoeboid processes, quite 

 unlike the strong, stiff cilia, which project from the intestinal, 

 epithelial cells of Amphistomum subclavatum. The greater 

 part of these granules doubtlessly belong to the swallowed food 

 of the parasite, although they do not betray the characteristics 

 of the granules found in the intestinal fluid. In preparations 

 made with the chrom-osmio-acetic fluid there are in the 

 neighborhood of the nucleus a number of blackened granules, 

 probably of a fatty or zymogenic nature. (Fig. 11.) They are 

 not pigmentary, for granules of this sort are distributed more 

 evenly in the half of the cell next its free surface, and have a 

 quite different tint and size. 



The epithelial cells are observable with diflSculty in the 

 living condition, and then only at certain points, in front of the 

 yolk-glands, and sometimes in the posterior arch of the 

 intestine. They have a clouded, granular appearance, which 

 prevents a definite ascertainment of their conditions of activity 

 while fresh. No amoeboid movements of the free ends of the 

 cells were observed. 



Structures answering to th-e " Kolben " of Kerbert were not 

 found here. All the cells of the intestinal epithelium are 

 alike, only differing in form at their free ends. The latter char- 

 acteristic gave at first some support to the opinion that the 



