28 
Gardiner and I to. — ■ On Mucilage-cells 
resin. The capitate mucilage-secreting hairs, which have 
been since shown to occur very commonly on the young 
stems, leaves and paleae of so many ferns, were first figured in 
the case of Polypodium aureum , L., by Suminski 1 in his ex- 
cellent and well-known drawings of young germinating plants. 
Hofmeister 2 represents similar hairs of Pteris aquilina , L., and 
those of the young scale (palea) of Polypodium serpens , Forst, 
and Kny 3 , in the case of Ceratopteris thalictroides , Brongn., 
figures the various stages in a developing scale in all of which 
the terminal mucilage-secreting hair is well shown. Hitherto 
but little notice had been taken of the more minute histology 
of the structures ; and it was Prantl 4 , and after him Sadebeck 5 , 
who described the mucilaginous character of the cell-contents. 
In the case of Osmunda regalis , L., de Bary 6 drew attention 
to the long septate mucilage-secreting hairs ; and quite 
recently Goebeler 7 , in his paper ‘ Die Schutzvorrichtungen am 
Stammscheitel der Fame,’ gives by far the most complete 
account extant, not only of the general distribution of secretory 
and protective hairs throughout the Filicineae, but also of their 
histology and physiological significance. 
We may now pass on to the literature of the resin-secreting 
glands, and here the unique intercellular hairs of Aspidium 
Filix-mas , Sw., claim the first place. These occur in the 
intercellular spaces of the rhizome and the base of the petiole, 
and as Sachs 8 afterwards showed in a similar position in the 
leaf-parenchyma. They were observed by Mettenius 9 , but to 
1 Suminski, Zur Entwicklungsgeschichte des Farnkraiiter, 1848. 
2 Hofmeister, Vergleichende Untersuchungen, Leipzig, 1851, and in Abh. d. 
Konig. Sach. Ges. d. Wiss., 1857. 
3 Kny, Entwick. d. Parkeriaceen, 1875. 
4 Prantl, Morphologie d. Gefasskryptogamen, 1881. 
5 Sadebeck, in Verhandlung d. bot. Ver. d. prov. Brandenburg, 1884. He 
figures young mucilage glands of Asplenium Serpentini. 
6 De Bary, Comparative Anatomy of Phanerogams and Ferns, p. 99. The hairs 
were first described by Milde, Monogr. generis Osmundse, Vindob. 1868. 
7 Goebeler in Flora, 1886. 
8 Sachs, Textbook of Botany, 2nd ed. p. 439. Sachs also figures the mucilage- 
glands of the sporangia of Aspidium Filix-mas. 
9 Mettenius, Filices horti Lipsiensis, Leipzig, 1856. 
