5o6 /■ PERCY MOORE. [Vol. X. 



Biondi-Ehrlich readily differentiates between these and the 

 adhesive glands of the acetabulum, which most resemble them, 

 staining the former more blue, the latter more red. Alcoholic 

 cochineal fails to stain the contents of these cells at all, while 

 the adhesive glands are deeply colored. The cell-walls and 

 nuclei, however, always stain deeply. The former are distinct, 

 but delicate, sometimes tensely stretched, sometimes, notably 

 in worms which have been inactive for a long time, wrinkled 

 and flaccid. Most of the abundant glairy mucus which en- 

 velops the resting worm is secreted by these glands. In the 

 quiescent condition of the worm the posterior sucker is firmly 

 fixed, the head and anterior somites are coiled ventralward, 

 about one and one-half turns, and the transparent mucous 

 covering thrown out as a protection. As it leaves the ductules 

 the secretion has an almost fibrous structure, which reminds 

 one of a spider's thread as it leaves the spinnerets, but this 

 soon disappears in the water. 



The lateral glands probably represent the setigerous epithe- 

 lium of the Enchytraeidae, etc. 



Filling up the basal portion of the upper lip is a conspicuous 

 gland, which may have a salivary function, and which differs 

 in appearance from any of the glands yet described. It is 

 developed from a tubular invagination of the oral epithelium, 

 just in front of the upper jaw (Fig. 9, sg), and, in the adult 

 consists of a single stratum of coarsely granular pyramidal 

 cells, opening into a short tubular duct, which is somewhat 

 eccentric in position, owing to the cells of the posterior wall 

 having their growth restricted by crowding against the muscu- 

 lar jaw-pad. A slight median dorsal constriction divides the 

 gland into two lobes. This gland is further remarkable from 

 the presence of a muscular sheath, which extends as a delicate 

 sheet from the dorsal region of the muscular jaw-pad, over its 

 dorsal and anterior faces, to the oral epithelium. The sheath 

 slips freely over the glandular epithelium and serves to elevate 

 the lip; and, perhaps, also to aid the flow of secretion from the 

 duct by pressure on its walls. 



Glandular structures, developed especially by the epithelia of 

 particular organs, will be described in their proper connection. 



