THE HIGHER CRYPTOGAMIA. 311 



well inter se as with the atmosphere, and with the (hitherto 

 entirely unobserved)* depressed empty space above the 

 vegetative centre or terminal bud of the stem. 



The second and the third frond also of the germinating 

 Botrychium are scale-like, of a whitish colour, and composed 

 of elongated cells containing very little solid matter ; never- 

 theless the second frond sometimes, the third always, have a 

 greenish tip (PI. XLII, fig. 9), which is the first indication 

 of the lamina of the frond. In the fourth frond this green 

 portion is more fully formed : it contains on either side two 

 or three feathery flaps, between the lowest of which the 

 rudiment of the fertile frond makes its first appearance in 

 the form of a hemispherical protuberance. It produces only 

 a few, usually two, simple ramifications. This pair of 

 fronds, after breaking through the sheathing portion which 

 forms the principal mass of the third frond, rises above the 

 surface of the earth during the next vegetative period, and 

 represents a diminutive moon-wort, not differing essentially 

 from the older ones. It is not yet ascertained whether, 

 during the subterranean growth of the germ-plant, one only 

 of the scale-like fronds is developed yearly, as is the case 

 with full-grown plants. It is very unlikely that such should 

 be the case : the formation of the first, second, and third 

 fronds probably takes place in the first vegetative period of 

 the germ-plant, which consequently would develope in the 

 second year the first green frond, and at the same time the 

 first spore-bearing frond. 



Each new pair of fronds makes its appearance near the 

 almost smooth end of the stem of the full-grown plant in 

 the form of a minute flatly-conical protuberance. The 

 basal sheathing portion is first developed by active multi- 

 plication of the cells, especially in the direction of a plane 

 passing through the median line of the organ and radial to 

 the longitudinal axis of the stem, so that the rudiment of 

 the pair of fronds destined to be developed in the third fol- 

 lowing spring covers the terminal bud of the stem, like the 

 cotyledons of a liliaceous plant. The apex of the frond- 



* This circumstance was not noticed by Presl and Mettenius, but was ob- 

 served by Roper in a paper which appeared after the publication of the above 

 observations. (See Bot. Zeit.,' 1859, p. 242.) 



