WAITE: ANTENNAL GLANDS IN HOMABDS AMEEICANUS. 163 



consists, however, of only the glandular epithelium of the vesicle wall, the 

 muscular layer — to be described later (p. 167) — being in this region 

 absent. Between the basement membrane of the epithelium of the 

 vesicle and the wall of the endsac there is a rich plexus of blood-ves- 

 sels, — branches of the sacculary artery, — some of which are shown 

 cut across in Figure 2 (i-as. sng.). 



The septa of the endsac, both complete and incomplete, consist each of 

 a fold of the epithelial lining of the sac (Plate 1, Figure 3, cl. sac. trm.), 

 embracing a sheet of connective tissue (tis. con't.) between its two lay- 

 ers. This connective tissue is highly vascular, being principally formed 

 of the walls of blood vessels and blood lacunae. The glandular epi- 

 thelium of the endsac forms of course a continuous layer, lining all com- 

 partments and investing all septa. It is everywhere a single layer thick, 

 and its cells have certain distinctive characters. In shape they vary 

 both according to location and to condition of activity. They are most 

 elongated on the dorsal wall (Figure 4) and at the place of junction 

 with the cells of the labyrinth ; most rotund on the ventral floor and on 

 the septa which rise from it (Figure 3, cl. sac. trm.). 



The difference of shape due to the state of activity is more striking. 

 Cells lying side by side (Figure 4) vary much in this respect. Among 

 shorter cells of nearly uniform diameter there are many elongated cells, 

 the free ends of which are expanded into globules often in diameter two 

 or three times that of the basal portion of the cell. The contents of 

 these swollen ends are less dense and stain less deeply than do the basal 

 portions of the cells. The globules become detached and pass to the ex- 

 terior, the lumen of the endsac being more or less filled with various 

 sized globules of this nature (Figure 4, gib.). Each, when detached, — 

 if free from mechanical pressure, — is spherical and contains a granular 

 clot nearly filling it. This clot is not homogenous, but made up of 

 granules of various sizes and degrees of opacity. Various progressive 

 stages in the constricting off of the globules from the cell are seen, so 

 that there can be no doubt that they arise primarily from the cells. 

 These globules seem to be composed of a mass of secretion products en- 

 closed in a capsule, which is part of the cell wall. They are not detached 

 cells, for they never contain a nucleus, nor, so far as I have seen, any 

 chromatin particles. Further, there are no evidences of nuclear division 

 in the glandular epithelium, as would probably be the case if these 

 globules were degenerate cells ; for if some cells became degenerate and 

 passed off, division would be necessary in the normal cells to make up 

 the loss. 



