237 
endothelium, the muscle layer and the core of loosely 
arranged peritoneal cells. In this and in several 
other processes in the same heart there is a large collec- 
tion of chlorogogenous granules in many of the peritoneal 
cells. These are shown in red in the figure, but they are 
naturally of a yellow colour. The granules are often 
ageregated into small heaps, sometimes lying in a vacuole. 
The outlines of the cells which are loaded with chloro- 
gogenous granules are difficult to distinguish. The proto- 
plasm of many of the peritoneal cells is vacuolated 
and of others is granular, but the granules are very minute 
and of a different nature from the chlorogogen granules. 
x 00! 
Fig. 34. Transverse section of a young specimen, 
showing the nuchal organ, below which are the two 
posterior brain lobes, an otocyst with its contained otoliths 
and the tube leading to the exterior, the two cesophageal 
connectives, the buccal mass with its sheath of muscles 
and its retractors, the retractors of the prostomium and 
nuchal organ, the muscles of the body wall, blood-vessels, 
&e. The upper portion of the brain lobes and the outer 
portion of each cesophageal connective contains nerve cells 
(diagrammatically shown in the figure). The fibrous 
portion of these structures is dotted. x 65. 
Fig. 55. Transverse section of a young specimen at 
the level of the openings of the glands into the esophagus. 
The partitions which partially subdivide the gland, each 
formed by a fold of the epithelium lining the gland and 
enclosing a vascular sinus, are seen. Also the muscles of 
the body wall and their blood-vessels; the oblique 
muscles; the nerve cord; the vesicle and external opening 
of the second right nephridium ; portions of two notopodial 
setal sacs and the blood-vessels connected with the alimen- 
tary canal. The ventral vessel and the two branches near 
