4i 8 Bower . — Studies in the Phytogeny of the Filicales . 
an ‘ Acrostichoid ’ condition. From these remarks it appears that the series 
of the Blechnoid Ferns has been unusually plastic in point of external form, 
a quality which has doubtless contributed to its successful seizure of stations 
by a very large number of species. 
Dermal Appendages. 
A very wide area of fact has shown the correctness of the conclusion 
that of the dermal appendages of Ferns the prior condition was the hair, 
composed of a single row of cells, branched or unbranched ; and that the 
flattened scale is a derivative state, and is shown by Ferns phyletically 
more advanced. This conclusion was clearly stated by Prantl in his 
memoir on the Schizaeaceae (p. 38), and that family illustrates the point as 
well as any that could be quoted. In certain series of Ferns such hairs 
bear terminal cells of a glandular character, often with mucilaginous con- 
tents ; in other ca§es the contents may be of the nature of resins or essential 
oils. The presence of such terminal glands often provides valuable features 
for comparison. 
Long ago, Gardiner and Ito made a careful investigation of such 
glandular hairs in Osmundci and Blechnum (Ann. of Bot., vol. i, p. 27). The 
glandular cells might in Blechnum be terminal either on a simple hair or on 
a flattened scale, and the secretion might be mucilage or resin. Through- 
out the genus Blechnum such hairs with large terminal glands are found. 
They occur also in Matteuccia intermedia. Similar glands, terminal either 
on hairs or flattened scales, are seen also in Brainea and Stenochlaena ; in 
Doodia and Woodwardia ; in Blechnum punctulatum , var. Krebsii, and 
Scolopendrium ; and in Asplenium. They are, in fact, general for the 
Blechnoid Ferns. The simple hairs of Plagiogyria also bear each a terminal 
gland of like character (Ann. of Bot., 1910, p. 427). The form of the 
dermal appendage which bears the gland may vary from a simple hair 
to a broad and flattened scale; and both types may be present on the 
same plant. When this is so, the scales are specially prevalent on the axis 
and base of the leaf, while the simple hairs preponderate distally. In 
Plagiogyria , hairs only are present, and there are no scales. This is 
probably a primitive state, and it appears to isolate Plagiogyria from the 
rest of the Ferns here treated. In Matteuccia intermedia , as in most Ferns 
of Cyatheoid affinity, broad scales cover the stock and leaf-stalk, but they 
diminish in size and number upwards, till on the pinnae they are replaced 
by simple hairs. With varying size and proportion, the same may be said 
of the genus Blechnum, but some of its species show a peculiarly effective 
protection of the young leaves by plentiful broad filmy scales. A climax 
of such scaly development, extending here to the distal end of the leaf, 
is seen in Woodwardia radicans, where simple hairs are almost entirely 
replaced by them ; and a similar state is seen in Asplenium obtusatum. 
