621 
Yendo. — -On the Mucilage Glands of Undaria. 
surface of the glandular cell-wall will have been relaxed and pressure 
released. In other words, the glandular cell must have been plasmolyzed 
unless it had a thin dilatable cell-wall. The difference in the degree of 
staining might have been due to the degree of turgescence rather than the 
chemical properties. But this is merely my supposition and needs further 
proof. 
Summary. 
1. Undaria has numerous glandular cells scattered in the lamina. 
2. As a rule, each glandular cell originates from a single cortical cell 
which is in contact with the epidermal layer. 
3. The epidermal cell upon a glandular cell degenerates as the latter 
develops, leaving a membranous coating over the gland. 
4. The function of the gland is possibly to secrete a mucilaginous 
substance. 
5. The glands found in the lamina of Hirome and Undariopsis will 
probably prove to be similar to those of Undaria in their mode of develop- 
ment and function. 
EXPLANATION OF PLATE XLVIII. 
Illustrating Prof. Yendo’s paper on the mucilage glands of Undaria. 
Fig. 1. Surface view of a portion of a pinnule stained in toto with aniline blue. The left side, 
shown in thick outline, indicates the margin ; the lower end is toward the rachis. a, b } c, various 
stages of development of the cryptostomata. x 54. 
Fig. 2. Cross-section of a pinnule, showing a gland with granular contents ; from fresh 
material, x 450. 
Fig. 3. Surface view of a supraglandular space ; from fresh material, x 450. 
Fig. 4. The same, with the three contiguous cells in course of degeneration, x 450. 
Figs. 5-7. Surface view of the supraglandular spaces, showing the stages of development. 
X 250. 
Fig. 8. Cross-section of a frond with two young glands, x 1050. 
Fig. 9. A gland at a stage a little more advanced. Two epidermal cells above the same gland. 
X 1050. 
Fig. 10. Two glands side by side, x 1050. 
Fig. 11. A glandular cell nearly completed ; typical form, x 1050. 
Fig. 12. Cross-section of one of the youngest pinnules of a sporophyllous frond, preserved in 
formalin, x 450. 
Fig. 13. Various stages of development of the glands. In the middle one the epidermal cell 
seems to have fused with the glandular cell, x 1050. 
Fig. 14. An abnormal gland, x 1050. 
