410 
frequently separated by nature for particular purposes, is proved by the pro- 
duction of pollen out of the cellular tissue of an anther, and by the general 
law of propagation that seems to prevail in flowerless plants, as Ferns, Lichens, 
Algae, and Fungi ; the same phenomenon may be therefore expected in Mosses. 
That the columella should be left in this dissolution of the tissue might be ex- 
pected, from its being a continuation of the seta or axis of developement, the 
tissue of which is more compact, and of course less liable to separation, than 
the looser tissue that surrounds it ; this is analogous to the separation of the 
pollen from the connectivum of most plants, or from parts only of the anther 
of all those genera which, like Viscum, AEgiceras, or Rafilesia, have what are 
called cellular anthers ; and to the very common separation of the placenta, 
or a portion of it, from the dissepiments, as in Bignoniaceae, Ericeae, and many 
others. That it is presumptuous in me, who lay no claim to reputation as a 
Crj^ptogamic botanist, to oAfer any opinion upon plants I have only occasionally 
stuched, I am fully sensible ; but I hope for the indulgence of the skilful Cryp- 
togamist, in consideration of this having been the first attempt to call his at- 
tention to the inquiry. 
Geography. Mosses are found in all parts of the world where the atmos- 
phere is humid : but they are far more common in temperate climates that in 
the tropics. They are among the first vegetables that clothe the soil with 
verdm'e in newly-formed countries, and they are the last that disappear when 
the atmosphere ceases to be capable of nourishing vegetation. The first green 
crust upon the cinders of Ascension was minute Mosses, they form more than 
a quai-ter of the whole Flora of Melville Island, and the black and lifeless soil 
of New South Shetland is covered with specks of Mosses struggling for ex- 
istence. How they find their way to such places, and under what laws they 
are created, are mysteries that human ingenuity has not yet succeeded in im- 
veiling. About 800 species are known. 
Properties. The slight astringency of Polytrichum and others caused 
them to be fomierly employed in medicine, but they are now disused. In the 
economy of man they perform but an insignificant part ; but in the economy 
of nature, how vast an end ! 
For the following list of genera I am indebted to the kindness of Dr. 
Hooker : — 
GENERA. 
§ 1. Bryace^e, Hook. 
{Seta terminalis.) 
II 1. Sphagne^, Brid. 
Sphagnum, L. 
^ 2. PHASCOIDEiEjAm, 
Phascum, L. 
Physedium, Brid. 
Pleuridium, Brid. 
Archidium, Brid. 
Voitia, Hornsch. 
Bruchea, Nestl. 
Saproma, Brid. 
^ 3. Gymnostomea:, 
Arn. 
Gymnostomum, 
Hedw. 
Hyophila, Brid. 
Hymenostylium, 
Brid. 
Rotfleria, Brid. 
Entosthymenium, 
Brid. 
Pyramidiura, Brid. 
Pyramidula, Brid. 
Hymenostomum, 
Brid. 
^ 4. Grimmie^, Arn. 
Grimmia, Hedw. 
Schistidium, Brid. 
Helicophyllum, Brid, 
Hydropogon, Brid. 
Dryptodon, Brid. 
Scouleria, Hook. 
Trichostomum, Hedw, 
Racomitrion, Brid. 
? Olomitrium, Brid. 
Leucoloma, Brid. 
Cinclidotus, Beauv. 
^ 5. Splachne^, Arn, 
Splachnum, L. 
Aplodon, Br. 
Systylium, Hornsch. 
Tayloria, Hook. 
Orthodon, B017. 
Cyrtodon, Br. 
Eremodon, Brid. 
Dissodon, Grev. et 
Arn. 
CEdopodium, Schw. 
^ 6. Orthotriche,®, 
Arn. 
Orthotrichum, Hedw. 
Ulota, Mohr. 
Brachypodium, Brid, 
Macromitrion, Brid. 
Leiotheca, Brid. 
Schlotheimia, Brid. 
Syrrhopodon, Schw. 
Trachymitrion, 
Hedw. 
Calymperes, Sw. 
Octoblepharum, 
Hedw. 
Leucophanes, Brid. 
Glyphomitrion, Brid. 
Drummondia, Hook. 
Zygodon, Hooker et 
Tayl. 
Codonoblepharum, 
Schw. 
? Teti aphis, Hedw. 
Tetrodontium, Schw. 
H 7. Weissie,®, Brid. 
Weissia, Hedw. 
Coscinodon, Spreng. 
Oreas, Brid. 
Discelium, Brid. 
. Catoscopium, Brid. 
Didymodon, Schw. 
Ceratodon, Brid. 
Pilopogon, Brid. 
Plaubelia, Brid. 
8. Dicrane®, Arn. 
Dicranum, Hedw. 
Orthotheca, Brid. 
Oncophorus, Brid. 
Trematodon, Mich. 
Campylopus, Brid. 
Thysanomitrion, 
Schw. 
H 9. Tortule®, Hook. 
Tortula, Hedw. 
Barbula, Hedw. 
Syntrichia, Hedw. 
Zygotrichia, Brid. 
Desmatodon, Brid. 
