292 R. T. GUNTHER. 
are seen to be situated in a space surrounded by a definite endothelium (e.), 
which separates the sense-organs from the mass of modified thread-cells com- 
posing the nettle-ring (#.7.). x 1000. Zeiss, apo. 4 mm., comp. oc. 8, 
cam. luc. 
Fic. 2.—The next section to the one figured in Fig. 1. Sense-organ B is 
seen in median section, and shows the difference between the granular basal 
cells and the refringent central cells very well. The mesogloea (ms.) forms a 
slight cup-like elevation round the base of the sense-capsule. The young 
sense-organ A is also cut near the median plane, and the mesoglcea is discon- 
tinuous between the organ and the endoderm. X 1000. Zeiss, apo. 4 mm., 
comp. oc. 8, cam. luce. 
Fic. 3.—Radial section through the manubrium of a female individual, in 
the region of the ovary. Ova (ov.) in various stages of development are 
readily distinguishable from the interstitial cells (s¢.) on account of their 
granular structure. The largest ova contain vacuoles (vac.), usually situated 
on the outer side of the nucleus. Covering all is a limiting epithelium of 
irregular cells (ec¢.). 400. Zeiss, apo. 4 mm., comp. oc. 4, cam. luc. 
Fic. 4.—Section similar to the one figured in Fig. 3, but from the sper- 
marium of a male individual. The layer of ectoderm cells (ect.1) nearest the 
mesoglea (ms.) gives rise to the cells of the second layer, the nuclei of 
which are alone visible (ect.*), and these in their turn break up to form the 
sperm-cells themselves (sp.) No spermatozoa tails have made their appear- 
ance in the stage figured. As in the case of the ovary, the entire organ is 
enclosed by a limiting membrane (ec/7.3). x 400. Zeiss, apo. 4 mm., comp. 
oc. 4, cam. luc. 
Fie. 5.—Radial section through corner of gastric cavity (g. c.) to show 
the point of junction between the endoderm of the manubrium (end. m.), the 
endoderm of the gastric wall of the umbrella (ezd.), and the endoderm 
lamella (exd. /.). All cell-walls disappear at the point of junction of the 
three layers. 
Fic. 6.—Radial section across the circular canal and through the base of an 
interradial tentacle (¢e.). The lumen of the circular canal (ec. ¢.) is continuous 
with that of the tentacle. The large ‘endodermal organ” fills up most of 
the lumen of the circular canal. On the outer side is seen a portion of the 
nettle-ring (7. 7.). 
Fic. 7.—Multinucleate corpuscles from lumen of the circular and radial 
canals. vac. Vacuole. chr. Chromatin. x 1000. Zeiss, apo. 4 mm., 
comp. oc. 8. 
Fie. 8.—Longitudinal section through a Medusa bud in the youngest stage. 
The bud is a mere hollow outgrowth of the wall of the manubrium, and its 
cavity (g. v.) is directly continuous with the gastro-vascular cavity of the 
parent. 
