THE MORPHOLOGICAL COMPOSITION OF PLANTS. 49 



ing separation to be arrested ; and the fructifying elements 

 will revert towards the ordinary form, and develop in con- 

 nexion with the parent. Turning to the Acrogens, wo 

 find among them, many indications of this transition from dis- 

 continuous development to continuous development. Thus the 

 Liverworts give origin to new plants by cells which they 

 throw off from their surfaces ; as, indeed, we have seen that 

 much higher plants do. "According to Bischoff," says 

 Schleiden, " both the cells of the stem (Jungermannia, biden- 

 tata) and those of the leaves (/. cxsecta) separate themselves 

 as propagative cells from the plant, and isolated cells shoot 

 out and develop while still connected with the parent plant 

 into small cellular bodies (J. violaced), which separate from 

 the plant, and grow into new plants, as in Mnium androgynum 

 among the Mosses." Now in the way above explained, these 

 propagative cells and proliferous buds, may continue de- 

 veloping in connexion with the parent, to various degrees 

 before separating ; or the buds which are about to become 

 fructifying organs, may similarly, under increased nutrition, 

 develop into young fronds. As Sir ~W. Hooker says of the 

 male fructification in Jungermannia furcata, " It has the ap- 

 pearance of being a young shoot or innovation (for in colour 

 and texture I can perceive no difference) rolled up into a 

 spherical figure." On finding in this same plant, that some- 

 times the proliferously-produced frond, buds out from itself 

 another frond before separating from the parent, as shown in 

 Fig. 46 ; it becomes clear that this long-continued connexion, 

 may readily pass into permanent connexion. And when 

 we see how, even among Phaenogams, buds may either detach 

 themselves as bulbils, or remain attached and become shoots ; 

 we can scarcely doubt that among inferior plants, less de- 

 finite in their modes of organization, such transitions must 

 continually occur. 



Let us suppose, then, that Fig. 73 is the frond of some 

 primitive Acrogen, similar in general characters to Junger- 

 iiannia epiphylla, Fig. 43 ; bearing, like it, the fructifying buds 



