500 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
cells of the rhizome of some of the species are infested by an endotrophic 
mycorhiza (vide infra , p. 504). 
Archegone of Ferns.* — Prof. D. H. Campbell corrects his previous 
statement that the ventral canal-cell is wanting in Struthiopteris ger- 
manica. Sections with the microtome exhibit it very clearly, and show 
that it is derived from the central cell. 
Rhizome of Ferns.f — According to Herr J. Yelenovsky, the lateral 
branches of the rhizome of Ferns do not always originate in the axil of a 
supporting leaf, but frequently from a true dichotomy. In Polypodium 
Dryopteris and Pliegopteris the branching is not perfectly dichotomous ; 
but in Aspidium Thelypteris it is regularly so ; both branches are equally 
provided with leaves of equal length and vigour, and spring from two 
terminal segments of equal size. The so-called adventitious buds of 
Pteris aquilina, Struthiopteris germanica, Nephrolepis tiiberosa, &c., are 
not altogether homologous to the adventitious buds of flowering plants ; 
since in the Ferns these structures are constant, arising regularly at 
definite spots, and are the sole source of the growth of the plant, there 
being no other mode of branching. The rhizome of most ferns divides 
without any regular law, often regularly monopodially or dichotomously, 
but the branches do not originate in the axil of a leaf. 
Apical Growth of Osmunda and Botrychium. i — Prof. D. H. Camp- 
bell finds considerable variation in the structure of the root-tip in the 
Osmundaceae. In the common American species of Osmunda , while the 
structure of 0 . cinnamomea agrees, in the mode of growth of the root-tips, 
very nearly with that of O. regalis , that of 0. Claytoniana approaches much 
more nearly to the appearance presented by ordinary leptosporangiate 
ferns. 
In the Ophioglossaceae, a similar difference was observed in the 
native American species of Botrychium , B. ternatum and B. Virginianum. 
Of these two species, the latter approaches much more nearly to the true 
Filices in the structure of its roots, as it does also in other respects. 
Structure of Ophioglossacese.§ — M. G. Poirault calls attention to 
the following points in the anatomy of the vegetative organs of the 
Ophioglossaceas ( Ophioglossum vulgatum and lusitanicum and Botrychium 
lunaria ). The sieve-tubes are destitute of callus, presenting a contrast 
to the structure in the normal Filices. The root grows by the seg- 
mentation of a single tetrahedral cell. The roots have a remarkable 
power of producing buds, which is most strongly displayed in Ophio- 
glossum vulgatum. This species is apparently always propagated in this 
way, the author never having seen a prothallium. 
Sphenophyllum.|! — Prof. J. S. Newberry describes six American 
specimens of Sphenophyllum , which he regards as probably not the 
foliage of Catamites , but as representing a peculiar and extinct family 
* Bull. Torrey Bot. Club, xviii. (1891) p. 16 (2 figs.). Cf. this Journal, 1888, 
p 618. 
f SB. K. Bohm. Gesell. Wiss., 1890 (2 pis.). See Bot. Centralbl., xlvi. (1891) 
p. 32. X Bot. Gazette, xvi. (1891) pp. 37-43 (1 pi.). 
§ Comptes Benefits, cxii. (1891) pp. 967-8. 
|| Journ. Cincinnati Soe. Nat. Hist., xiii. (1891) pp. 212-7 (1 pi.). Cf. this 
Journal, ante , p. 73. 
