EXPLANATION OF PLATES XXX and continued. 
the green-coloured cartilaginoid tissue of the abumbral wall of the mar- 
ginal canal. 
Fig. 7. — Two cells of the adumbral wall of the marginal canal, show- 
ing their rounded form and dark greenish-brown-coloured concretionary 
granules. 
Fig. 8. — One of the marginal bodies as seen in the living condition. 
The attached pole is the lower in the figure. A greenish granule similar to 
those of the endoderm cells is seen in the body to the left. 
Fig. 9. — A similar body after the action of dilute acetic acid. Surface 
view. 
Figs. 10 and 11. — Two marginal bodies or “ refringent sense-bulbs ” 
seen in optical section after the action of osmic acid. tec. cortical cells or 
tentacle-ectoderm ; axen. medullary cells or endodermal axis. 
Figs. 12 and 13. — Earliest stage in the development of a “ marginal 
body” from a medusa nearly half an inch in diameter. ~End. endoderm of 
the marginal ring with green-coloured cell-substance ; 'Ect. colourless ecto- 
derm ; axen, axial cell of the marginal body derived from endoderm 
and coloured by green particles; cc. tubular capsules of neighbouring 
“ bodies.” 
Fig. 14. — Later stage in the development of the marginal body and its 
tubular capsule ; End. endoderm of the marginal ring ; axen. axial endo- 
derm cells of the ‘'body”; Ect. ectoderm of the velum; tec. tentacular 
ectoderm or cortical cells of the marginal body ; cc. cavity of the tubular 
capsule. 
Fig. 15 — A later stage. End. endoderm of the marginal ring ; nerve- ‘ 
ring ; Ve. velum ; gr. greenish granules characteristic of the endoderm ; axen. 
axial endoderm or medullary cells of the marginal body ; tec. cortical cells 
or tentacular ectoderm of the same ; Cag. tubular capsule. 
Fig. 16. — A still later stage ; axen. axial endoderm or medullary cells of 
the marginal body ; tec. tentacular ectoderm or cortical cells of the mar- 
ginal body; cc. cavity of the ectodermal tubular capsule; cap. wall of the 
capsule formed by the velar ectoderm. 
Fig. 17. — Early stage in the development of a marginal body, in which 
the form of a tentacle is abnormally assumed ; End. endoderm of the mar- 
ginal canal ; Ect. ectoderm of the abumbral velar surface ; axen. enlarged 
axial endoderm cell, with green granules. 
Fig. 18. — Abnormally developed marginal body devoid of capsule and 
having the form of a small free tentacle ; End. endoderm ; Cap. capsule of 
a neighbouring marginal body; axen. axial endoderm cells forming a 
spherical group ; ect. tentacular ectoderm here having the form of a 
tentacle instead of closely investing the axial endoderm-sphere. 
Fig. 19. — Abnormal capsule developing without any tentacular element, 
that is, without a marginal body ; End. endoderm ; cc. cavity of the cap- 
sule : Cap. wall of the capsule ; x. nerve-ring. 
Fig. 20. — Abnormal marginal body (seen in optical section) which has 
broken away from its attachment to the marginal ring and is lying free in 
the distal end of its tubular capsule. The body has taken on the form of 
a spherical cyst, and shows the cortical cells forming the wall of the cyst, 
whilst within project the large endodermal cells. 
