5 2 
Gardiner and I to. — On Mucilage-cells 
Fig. 5. Mucilage-gland from young leaf representing the ‘ clear-drop ’ stage of 
the mucilaginous contents. 
Fig. 6. A slightly older gland. The drops appear to have clubbed together into 
an irregular lobular mass. Reagents, or even careful examination of fresh material, 
show that the drops are in reality quite distinct from one another. The drops 
display a distinct granulation. 
Fig. 7. Mature gland of Blechnum brasiliense. The contents show a differentia- 
tion into central, dark and granular core, and a clear and highly refractive 
peripheral portion, which exhibits signs of layering. 
Fig. 8. Similar cell from the leaf of Blechnum occidentale. 
Fig. 9. Terminal mucilage-gland from a palea, showing the granular mucilaginous 
contents which apparently possess quite a homogeneous structure. In spite of the 
disorganisation, on account of the complete breaking down of the endoplasmic 
framework, the mucilage is still present as a number of isolated drops. These may 
be demonstrated by swelling with water, and staining with methylene-blue. Note 
the disintegrated nucleus and the mode of rupture. 
Fig. to. Gland from leaf. The drops exhibit differentiation into droplets. The 
nucleus and plastids are fairly well shown. 
Fig. 11. A similar gland from a palea. 
Fig. 12. A similar gland from leaf at a later stage than Fig. 10. 
Fig. 13. Several isolated drops from a leaf gland. 
Fig. 14. Early stage in the development of gland-bearing hair. The terminal 
cell is that which becomes converted into the mucilage-gland. 
Fig. 15. Older gland-cell. Note the nucleus, the plastids, and the strands of 
protoplasm stretching from the nucleus. Vacuolation is now well marked. 
Fig. 16. Gland from young leaf treated with osmic acid. The first formation of 
the young mucilage-drops may be observed taking place around the primordial 
utricle, and in the strands of protoplasm. Certain of the contents of the vacuole 
of a mucilaginous nature have become contracted by the action of the reagent. 
Fig. 17. More advanced gland. The drops now numerous, and some even show 
the droplet stage. The basipetal formation of new drops is in this instance shown 
very clearly. 
Fig. 18. Young cell after treatment with chromic acid. The clear spaces which 
mark the points of origination of the drops are seen from the outside. The half- 
dozen or so of the very clear circular spots, although they simulate the true 
formation, are in reality produced in consequence of the shrinking of the proto- 
plasm from the wall at several small isolated areas, through the dehydrating action 
of the reagent employed. The impermeability of the mucilaginous cell contents 
causes the penetration of the reagent to take place with great difficulty, and often 
forces the protoplasm to give way. 
Fig. 19. Gland from leaf containing drops which exhibit but little definition. 
Note the nucleus and the protoplasmic framework. This gland was stained with 
iodine. 
Fig. 20. Similar gland with unusually clear contents. Drawn from fresh 
material mounted in water. 
Fig. 21. Two glands from young leaf. The smaller is a resin-gland. The 
larger secretes mucilage, and shows the ‘ clear-drop ’ stage. 
