ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 415 
is readily distinguished from the tissue of the ligule proper by the small 
size of the cells filled with protoplasm. The position of this tissue,, 
between the conducting xylem and the ligular tissue, indicates that it is 
intended for the rapid passage of fluids. Its purpose appears to be 
similar to that of the endoderm of roots, combining firmness with great 
permeability. 
Apogamy and Development of Sporanges on Fern Prothallia.* — 
Mr. W. H. Lang gives the results of experiments carried on for two- 
and-a-half years in the cultivation, under slightly abnormal conditions, 
of the prothallia of a number of ferns, chiefly cultivated varieties. In 
all cases the prothallia which would, under normal conditions, have pro- 
duced normal embryos, became apogamous after a longer or shorter 
period. The conditions which produce this result appear to be preven- 
tion of contact with water, and exposure to direct sunlight. The degree 
of apogamic variation presented great variety. The author regards these- 
departures from the normal development of the thallus, not as reversions 
in the ordinary sense, but as indications of the capability of direct 
response to altered conditions possessed by the gametophyte ; showing 
that the sporophyte and the gametophyte are modifications of a similar 
form. Originating from algal organisms of a flattened form, prolonged 
drought and the influence of direct sunlight might induce directly a 
change of form into a cylindrical body, accompanied by the substitution 
of a reproductive organ forming dry reproductive cells, or spores for 
those adapted to an aquatic existence. From these spores separated 
from the parent, a sexual individual would arise, since germination could 
take place only in a damp spot ; and thus an alternation of sexual and 
non-sexual generations might be brought about. 
Muscineae. 
Classification of Leucobryacese.t — M. J. Cardot proposes a new 
classification of the Leucobryacese, founded chiefly on the anatomical 
characters of the leaf. The Leucophanese, comprising the single genus 
Leucophanes, are first of all separated off, from the presence of a sclerified 
bundle in the mid-vein ; the remainder of the order being divided into 
the tribes Leucobryeae, Octoblepharese, and Arthrocormeae. M. Cardot 
reckons 176 species in the Leucobryaceae, arranged in nine genera, of 
which two are new, Cardotia, separated from Leucobryum , and Exodictyon , 
distinguished by the peculiar form of the mid-vein, which is often 
papillose. 
Nanomitrium.J — Mr. E. S. Salmon gives an account of this genus of 
Musci, hitherto regarded as cleistocarpous. The capsule (in N. tenerum)> 
possesses a distinct zone of specialised cells, delicate, narrow, and 
transversely elongated, clearly marking off the upper part of the capsule 
as a lid. Similar rows of cells were found in N. synoicum and Austini , 
but not in N. sequinoctiale, which is truly cleistocarpous. The capsule 
possesses stomates, and shows a similar structure in all essential points- 
to that of Ephemerum. The zone of differentiated cells by which a 
* Phil. Trans. R.S., cxc. (1898) pp. 187-238 (5 pis.). Cf. this Journal, 1897, 
p. 223. t Rev. Bryol., xxvi. (1899) pp. 1-7 (1 pi.). 
x Journ. Linn. Soc. (Bot.), xxxiv. (1899) pp. 163-70 (1 pi.). 
