82 



phrasta, Aloe, Echeveria, Gloxinia, and Cotyledon, may be pro- 

 pagated by leaves; healthy leaves of these plants are chosen, 

 they are cut off close to the stem, and then placed singly in 

 small pots in a light sandy soil. The leaves are covered with 

 a bell-glass which must be open at the top. In the course of 

 eight weeks the leaves become cartilaginous, put forth roots, 

 and then very soon a young plant appears above ground. 



It is desirable that this subject should soon be more fully 

 investigated, for we know at present that the emission of 

 young plants from leaves may take place in several ways ; first 

 by a production of true buds, as in Bryophyllum, and partly also 

 in Ceratopteris ; and secondly, by a previous formation of 

 gems, as in Ornithogalum thyrsoides, Ranunculus bulbosus, 

 cabbage leaves, &c. In M. DeCandolle's Vegetable Physi- 

 ology, (ii. p. 118.) M. Keeper has brought together several 

 other cases of the kind. 



I have again drawn attention to the increase of mosses by 

 gems*, in which way, at least, several species of mosses propa- 

 gate quite as plentifully as by true spores ; Mnium androgy- 

 num., L., is the most known in this respect. A drawing an- 

 nexed to the article of the extremity of a similar gemmal pe- 

 tiole exhibited a number of petiolated gemmae which subse- 

 quently drop off from the stalks which become brown. Mr. 

 G. Dickie has also published several observations on the 

 same subject f; he saw in the gemmae of Bryum (Mnium) 

 androgynum on their first appearance nothing more than 

 simple minute transparent vesicles of an oval form. I per- 

 ceived in them immediately after their first appearance ex- 

 tremely delicate greenish masses which were converted into 

 globules, and were again partially employed in the interior for 

 the formation of new parietes. Mr. Dickie says, that these 

 gemmae in their mature state contain a substance of granular 

 appearance, but no mention is made of their cellular struc- 

 ture ; the drawings unfortunately can hardly be termed recog- 

 nizable. According to my subsequent observations, there is 

 first formed in the simple elongated vesicle which occurs as the 



* Einige Worte iiber das Vorkommen von Brutknospen bei den Laub- 

 moosen. Wiegmann's Archiv, 1837, i. p. 424. 



f Observations on the Gemmae of Bryum androgynum. Magazine of 

 Zoology and Botany, vol. ii. p. 226. 



