26 HOFMEISTER, ON 



cells thus formed divide by laterally inclined longitudinal 

 septa, and so on, as in the case of the origin of the middle 

 shoot. The like process is repeated in the angles at both 

 sides of the new shoot, soon after the commencement of its 

 formation. A shoot originates in each angle, which unites 

 in growth with the median shoot, on the side which is 

 turned towards the latter. By this means a new shoot is 

 formed on each side of the middle segment of the fore edge 

 of the young plant (PI. IV, fig. 19), which new shoot, in 

 consequence of its being composed of three united shoots, 

 is tripartite at its fore edge. The flat cellular masses which 

 thus originate unite in growth firmly and intimately with 

 the middle shoot, by the edge which is turned towards the 

 latter. The new shoots, composed of these amalgamated 

 cellular bodies, protrude from the indentations of the 

 fore edge of the young plant, in consequence of the 

 commencement of longitudinal expansion in its basal 

 cells ; by their expansion, the middle lamellae which are 

 united _to them are drawn out laterally. Their form is 

 now a complete repetition of that of the germ-plant in 

 its earliest stage : the fore edge exhibits a short, spatula- 

 shaped median segment, and two lateral wing-shaped ones. 

 The subsequent ramification takes place in like manner. 

 There is one invariable rule for the entire development of 

 the plant, commencing from the formation of the middle 

 shoot of the germ-plant : the rule is, that each shoot has its 

 origin in the amalgamation of three shoots, which are formed 

 almost contemporaneously in one of the indentations of the 

 fore edge of an older shoot. Each new shoot, therefore, 

 exhibits at its first appearance two indentations of the fore 

 edge. According to the ordinary rule, new shoots are 

 formed only in those indentations which point out the 

 boundaries of the three amalgamated shoots. Hence arises 

 the furcate ramification of the plant (PI. IV, figs. 19 22). 

 The growth of each shoot is limited.* 



* Bischoff considers that the first shoot of the germ-plant of Pellia is a prothal- 

 lium, distinct from the subsequent shoots. ('Handb. d. Terminologie, 5 ii, 733 ; 

 'Botan. Zeitung,' 1853, 115.) As, however, the first shoot is not distinguish- 

 able in any essential particulars from the later ones, I agree with Gottsche 

 ('Bot. Zeitung,' 3858, Anhang, 16) in thinking that there is no ground for this 

 distinction. 



