202 I10FMEISTER, ON 



the cell of the second degree, contiguous to the mouth 

 of the archegonium, which has been cut off from the 

 stem-cell. This cell of the second degree is the primary 

 cell of the frond. 



That moiety of the primary cell of the principal shoot 

 which adjoins the first cell of the primary abortive axis is 

 considered to be a cell of the first degree, the principal rea- 

 son for which is, that at a later period, and when the germ- 

 plant is more developed, the cell in question appears as 

 the apical cell of the stem. It would be a simpler mode of 

 settling the rank of the cells, if that cell were con- 

 sidered to be of the first degree, in which the successive 

 divisions take place, not only at the earliest period, but in the 

 primary direction"; and according to this method there 

 would be no doubt that the primary cell of the stem, consi- 

 dered in relation to that of the frond, must be looked upon 

 as a cell of the second degree ; an opinion which might be 

 made use of in support of the theory of the origin of the 

 fern-stem from the amalgamation of the stalks of the 

 fronds.* As, however, there are but few plants which ex- 

 hibit so manifest a terminal bud (around and under which 

 the appendicular organs take their rise), as the ferns do 

 when they have attained some growth, it follows that here, 

 as in the similar instances of monocot}dedonous embryos, 

 it is necessary in forming an opinion as to the rank of the 

 cells, to have regard to the condition of the plant at a 

 period subsequent to the formation of the cells in question. 



In the two species immediately under consideration, the 

 cell-succession in the first frond agrees substantially with 

 that in the later ones, but at the same time it differs consi- 

 derably. The surface of the first frond is, however, in its 

 inception, parallel to that of the prothallium, as is the 

 case in all the Polypodiacese which have been hitherto ob- 

 served. The primary cell of the root divides in the first 

 instance by septa turned towards the neighbouring cells ; the 

 division takes place twice by means of opposite septa (concave 



* Considerations of this nature may have led Nageli to deny that ferns have 

 leafy stems (' Zeitschrift fur wiss. Botanik,' Heft 3 and 4, p. 148) ; Han- 

 stein's notion of the fern-stem also rests upon this foundation ('Linnfea,' 

 1848). 



