ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
637 
spore ; and the apex soon becomes occupied by a cellular tissue. The 
process corresponds closely to that of the formation of endosperm in 
seeds ; and the author holds that Isoetes presents, among Pteridophyta, 
the nearest relationship to Flowering Plants. 
Affinities of the Filicineae.* — Prof. D. H. Campbell dissents from 
Bower’s theory! that the Hymenophyllaceae represent the most primitive 
form of the Filicineae, and are probably derived from some form inter- 
mediate in character between existing bryophytes and the higher green 
algae. From a comparison of the oophytic and sporophytic generations 
in the various orders, he has come to the conclusion that the Ophio- 
glossaceae must be placed at the base of the Filicineae; from them 
sprang two main branches, one through the Marattiaceae, possibly termi- 
nating in the Cycadeae, the other through the Filices, giving rise to two 
branches ending in the two heterosporous groups, the Marsiliaceae and 
the Salviniaceae. According to this view the Hymenophyllaceae must 
be regarded as a degenerate group from the leptosporangiate Filices, the 
simple prothallium and sporophyte being the result of their semi- 
aquatic habit. 
Oophyte of the Gleicheniaceae.J — Herr N. W. P. Kauwenhoff has 
succeeded in germinating the spores of several species of Gleichenia , 
and in following the development of the archegones and antlierids on 
the prothallium, which differs in no essential point from that in other 
ferns. The growth of the prothallium is exceedingly slow. It is at 
first filiform, and the antherids appear near its apex ; subsequently it 
becomes club-shaped, and they then make their appearance over almost 
its whole surface, even on the upper side. Finally it becomes heart- 
shaped, and the archegones are then formed chiefly near the apex on 
the under side. Occasionally two oospheres are impregnated on the 
same pro thallium. The epidermal cells of the root spring from the 
lateral segments and not from the apical segments of the apical cell. 
There is a strong tendency towards dicecism in the prothallium, large 
numbers of archegones being borne on prothallia which produce only a 
single antherid or none at all. The prothallium sometimes grows to 
a great size, remaining quite barren, and not unfrequently exhibiting 
prolification. The spores have three coats. 
Sclerotized Elements in the Tissues of Eerns.§ — Dr. G. Walter 
has investigated the structure, chemical nature, and development of 
the brown- walled sclerotized elements in the tissue of thirty-eight 
species of fern, with special reference to the “ supporting bundle ” of 
Russow. 
While in the aerial stem of the tree-ferns the predominant form 
of the sclerenchyme is prosenchymatous, in the creeping rhizome of 
ferns with a dorsiventral structure it has chiefly a parenchymatous 
character. The “ supporting bundles ” which frequently occur in the 
creeping rhizome when the leaves are in two rows consists of isolated, 
usually parenchymatous strings of sclerenchyme in the fundamental tissue. 
* Bot. Gazette, xv. (1890) pp. 1-7. f Cf. this Journal, ante , p. 66. 
X Arch. Neerl. Sci. Exact, et Nat., xxiv. (1890) pp. 157-231 (7 pis.). 
§ Luerssen u. Haenlein’s Biblioth. Bot., Heft 18 (1890) 21 pp. and 3 pis. 
