1901.] NATURAL SCIENCES OF nilLADELPIIIA. 697 



Fig. 36 shows a small branch of the glandular ridge, on the sur- 

 face of which are several clusters of rhabdites. The section has 

 passed through the centre of the branch, exposing the central 

 connective tissue core, the lightly shaded area, Cn. T. No nuclei 

 have been seen in the rhabdite cells, probably owing to the great 

 number and the close proximity of the glandular secretions. 



The inner epithelium of the ventral surface is of quite a different 

 character. A certain amount of interstitial connective tissue is 

 present at the base, but there are no elevations. The most promi- 

 nent constituents of the epithelium are the large pink-staining 

 (hrematoxylin-eosin) gland cells, fig. 40, GL^. These cells are 

 quite elongated, the distal ends are large, and the proximal ends 

 are narrowed into a slender stalk. The cell body is entirely filled 

 with the granular secretion, and the nucleus lies just above the 

 stalk. Between the gland cells are very slender cells, somewhat 

 resembling epithelial supporting cells in shape. The nucleus is at 

 the base of the slender cell body, and in the distal cytoplasm may 

 be found one, or sometimes two, rods shaped like a thorn, with 

 flat base and pointed end. The base is embedded in the cyto- 

 plasm, the pointed ends project beyond the cell. These structures, 

 fig. 40, Th., stain a deep blue, hrematoxylin-eosin ; brownish with 

 the Ehrlich-Biondi stain. 



The Posterior Region. — The diameter of the proboscis in the 

 posterior region, fig. 41, is constantly decreasing, until at the 

 extreme tip it measures only .04 mm. 



The outer epithelial cells, fig. 39, o.Ep., like those of the ex- 

 treme anterior region, are ratlier brick-shaped cells with abundant 

 cytoplasm, and do not form a flattened endothelium. The muscle 

 layers have decreased relatively to the other tissues; and instead of 

 the nervous plexus of the middle region, there are, again, two 

 separate lateral nerves, P.X. The amount of connective tissue, 

 Cn. T.N., has increased, and as the nuclei of these cells are large, 

 with but little cytoplasm, the effect produced is that of a layer of 

 undifferentiated tissue. The glandular ridge has disappeared, and 

 the inner epithelium is of a uniform character, consisting of pink- 

 staining gland cells, GV.j, like those in the ventral epithelium of 

 the middle region. 



alcohol ; while they are ewollen and quite unrecognizable with Flemming's 

 fluid. 



