in Blechnum and Osmunda. 
53 
Fig. 22. Young gland after treatment with ten per cent, sodium-chloride-solution. 
Fig. 23. Older gland similarly treated. In this the drops were in process of 
formation. 
Fig. 24. Gland in which the protoplasm has formed an unusual quantity of 
tannin. In osmic acid. 
Fig. 25. A similar gland in its fresh state. 
Fig. 26. A gland of the same nature as Figs. 24 and 25. Note the formation of 
drops and the peculiar position of the nucleus. 
Fig. 27. Mucilage-gland undergoing rupture. The remains of the nucleus and 
ectoplasm continue in the cell. The ectoplasm still shows on its membrane traces 
of the reticulation and arrangement associated with the formation of drops. In 
osmic acid. 
Fig. 28. Second mode of escape of secretion. See text. 
Fig. 29. A cell after the escape of secretion. Remains of ectoplasm apparent. 
Fig. 30. Ruptured gland, showing fungus-mycelium which is now feeding on the 
remains of the ectoplasm. 
Fig. 31. Resin-gland from palea. The secretion is collected under the raised 
cuticle. In osmic acid. 
Fig. 32. Resin-gland after treatment with picronigrocin. Note the lenticular 
nucleus and the protoplasm which is collected towards the cell-apex, and there 
exhibits marked granularity. 
Fig- 33. Two views of a very young leaf of Osmunda regalis : m — the places 
where the mucilage-hairs are to be found in the greatest number. 
Fig. 34. Young mucilage-secreting hair. The cells are in various stages of 
development, and the growth is markedly basipetal. The starch-grains are 
especially situated in the protoplasmic strings, and in the upper cells the callosed 
and perforated transverse walls may already be observed. 
Fig. 35. Young woolly hair. In the clear cells towards the apex the cells are 
particularly rich in tannin. (This hair is taken from a leaf which had been for a 
short time removed from the plant. The peculiar aggregation of the starch-grains 
in the protoplasmic strands is somewhat abnormal. In quite fresh cells they are 
found around the primordial utricle. Fig. 34 has also been somewhat affected by 
the treatment to which it was subjected.) 
Fig. 36. Portion of a branched mucilage-secreting hair, showing the transverse 
walls and the two callus-plates belonging to each. The whole system (walls and 
callus) shows perforation. 
Fig. 37. Portion of a young woolly hair cell with callus well developed on one 
side of the transverse wall. 
Fig. 38. Young stage of development of mucilage-hair. 
Fig. 39. Slightly older stage. 
Fig. 40. Semi-diagrammatic optical section of mature mucilage-cell after 
treatment with iodine. Note the differentiation into layers, the drop-formation, 
the protoplasmic reticulum and the disorganised nucleus. 
Fig. 41. A similar cell from the outside. The mode of drop-development is 
quite apparent from this point of view. Some of the reticulation and formation of 
circular areolae is due to the disorganising starch-grains. The distinction between 
