PHARYNGEAL GLAND-CELLS OF EARTHWORMS. 
285 
EXPLANATION OF PLATE 19... 
Illustrating Prof. J. Stephenson’s paper, “On the So-called 
Pharyngeal Gland-cells of Earthworms.” 
Fig. 1. — Pheretima lieterochseta ; dissection of anterior end. 
c', Masses of chromopliil cells on pharynx; c 2 , upper, and c 3 , lower 
cellular masses in segment V, behind pharynx ; d.v., dorsal vessel ; 
m 1 , m 2 , muscular strands emerging from masses of chromopliil cells ; 
n, masses of micronephridia ; 'pin., pharynx; 4/5, 5/6, the corresponding 
septa, the latter turned back. X 8. 
Fig. 2. — Chromopliil cells from the pharyngeal mass of Pheretima 
posthuma. X 1250. 
Fig. 3. — Individual chromophil cells from Pheretima hetero- 
chseta. x 1650. 
Fig. 4. — Portion of the surface of the pharyngeal mass in Phere- 
tima lieterochseta, showing the general characters of the cells, 
clefts between the cells, and, at this place, entire absence of capsule. 
The surface of the mass is below in the figure. X 1000. 
Fig. 5. — Chromophil cells at some depth in the pharyngeal mast 
of P h e r e t i m a h a w a y a n a, undergoing transformation into connective 
tissue, n, Nuclei whose stainable cytoplasm has undergone conversion, 
and which are themselves becoming fainter ; m, mass of staining 
material, apparently without nucleus. X ca. 1250. 
Fig. 6. — Helodrilus caliginosus; dissection of anterior end 
c'-c 4 , Lobular masses of chromophil cells on pharynx; m, muscular 
strands emerging from the masses ; 5/6, 6/7, the corresponding septa 
(the first few septa are absent or unrecognisable). X 6. 
Fig. 7.— Helodrilus parvus, an approximately median longitudinal 
section. c\ Lobular masses of chromophil cells in segment IV, on dorsum 
of pharynx ; c 2 , the same in segment V ; c 3 , the same in segment VI ; 
cv, a portion of the latter appearing ventrally ; c.g., cerebral ganglion ; 
d, dorsal mass of the pharynx, consisting of connective tissue and 
muscle strands; ces., oesophagus; pli. div., dorsal diverticulum of 
pharynx; v.n.c., ventral nerve cord; 4/5, 5/6, 6/7, the corresponding- 
septa. X 40. 
Fig. 8. — Chromophil cells of Helodrilus parvus, x 1250. 
Fig. 9. — Chromophil cells of non-sexual Pheretima at some depth 
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