480 SUMMARY OF CTJBRENT RESEARCHES RELATING TO 



active movements of the spores themselves depend upon unequal 

 lignification of the elaters. 



The structure of the sporange of Lyeopodiacese and the macro- 

 sporange of Selaginellacese is nearly uniform, and was studied in 

 Selaginella, Psilotum, Tmesipteris, and Isoetes. The outer walls of 

 the epidermal cells are composed of pure cellulose, while the inner 

 and side walls are lignified, and dehiscence is caused by the outer 

 face of the cells contracting more than the inner face in dry air. 



Vascular System in Davallia.* — M. A. Trecul classifies the 

 species of this genus of ferns under four sections — Eudavallia, Leuco- 

 ategia, Microlepia, and Odontoloma — and describes the structure of 

 the fibrovascular system in each. 



In Eudavallia (D. pentaphylla, stenocarpa, canariensis, and elegans) 

 there are in the central region of the stem two principal bundles, 

 placed at some distance one above the other and parallel, the lower 

 one being usually the larger. A transverse section shows other 

 slenderer bundles, arranged in a curve on each side, and forming a 

 network between the insertion of the superposed fronds. In each 

 petiole are two anterior, and one, two, or three dorsal bundles, which 

 may be wanting in the smaller fronds. 



In Microlepia (D. trichosticha and strigosa) and Leucostegia (D. 

 immersa and Novse Zelandise) the cellulo-vascular system of the stem 

 takes the form of a continuous tube, open only at the insertion of 

 the fronds. Odontoloma {D. rejpens) also has a tubular vascular 

 system in the rhizome, but is not regularly thickened, as in the two 

 preceding sections, and presents also other points of difference in its 

 structure, which are described in detail. 



Stolons of Nephrolepis.t — M. A. Trecul replies to M. Lachmann's 

 contention J that these organs are cauline in their origin. He 

 denies M. Lachmann's statement that it is always the case in fern- 

 stems that the vascular bundles are arranged radially, and that the 

 small primordial vessels are always on the external face of the 

 bundles, as in the roots. On the contrary, in the stem of many 

 species, the bundles are disposed parallel to the circumference, and 

 there are no small primordial vessels — annular, spiro-annular, reticu- 

 lated, or spiral — except at the margin of the network, and only below 

 the insertion of the petiolar bundles. M. Trecul gives a number of 

 examples of this structure. He does not consider the absence of a 

 root^cap as by any means conclusive evidence that the structures iu 

 question are not of radicular origin, 



Muscmese. 



Peristome of Mosses.§ — Pursuing his researches on this subject, 

 M. Philibert now describes the peristome of several species of Bryum, 

 including one new one, B. Kindbergii. He regards the series of forms 



* Comptes Eendus, ci. (1885) pp. 1453-9. t Ibid., pp. 915-20. 



t See thie Journal, v. (1885) p. 1033. 



§ Bev. Bryologicjue, xix. (1885) pp. 81-5, Cf, this Journal, v. (1885) pp. 100, 

 1035, 



