PHARYNGEAL GLAND-CELLS OF EARTHWORMS. 
265 
be seen, are found numerously in young specimens, where the 
chromophil cells have undergone little change. 
I am doubtful if it is always possible to distinguish between 
these smaller nuclei and the last stage of transformation of 
the nuclei of the chromophil cells. But, in spite of the fact 
that discrimination of the separate elements may be impossible 
in the adult, it seems necessary to attribute a double origin to 
the connective tissue of this region. 
The Capsule. — In view of what will be said later, the 
relation of the cells to the peritoneum is of interest. The 
lobular masses are surrounded by a thin capsule, — a membrane- 
like expansion, with fairly numerous ovoid or flattened nuclei, 
which show scattered chromatin granules but no nucleolus. 
The membrane bridges over the clefts between adjacent cells 
at the surface of the mass ; it is in many places distinctly 
differentiated from the underlying cells, staining pink with 
eosin, and hence sharply marked off from the chromophil 
cells beneath. In places the membrane may contain numbers 
of brown chloragogen grains ; in this condition it may be 
still a moderately thin (3-4 n) membrane, or it may be swollen 
so as to be fairly described as being composed of somewhat 
flattened chloragogen cells ; but there are no chloragogen 
cells of the usual elongated type. In places the capsule is 
absent, and the — sometimes indefinite — limits of the chromo- 
phil cells themselves form the boundary of the mass. 
PHERETIMA HETER0CH2ETA. 
G-eneral description (PI. 19, fig. 1).— In this species the 
cells, as in P. posthuma, form lobular masses on the 
pharynx (c 1 ) ; but in addition lobules composed of chromo- 
phil cells extend backwards, dorsal to the oesophagus, into 
segment Y (c 2 , c 3 ), where they are altogether behind the 
pharyngeal region of the alimentary tube. Crossing seg- 
ment Y in a more or less longitudinal direction are a 
number of muscular bands which pass backwards from the 
pharyngeal mass in front; the more superficial of these (m 2 ) 
