THE MORPHOLOGICAL COMPOSITION OF PLANTS. 53 



and texture I can perceive no difference) rolled up into 

 a spherical figure.&quot; On finding in this same plant, that 

 sometimes 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 Phas- 

 nogams, buds may either detach them 

 selves as bulbils, or remain attached and 

 become shoots; we can scarcely doubt 

 that among inferior plants, less definite in 

 their modes of organization, such transi 

 tions must continually occur. 



Let us suppose, then, that Fig. 73 is 

 the frond of some primitive Archegoniate, 

 similar in general characters to Pellia 

 epiphylla, Fig. 43; bearing, like it, the 

 fructifying buds on its upper surface, 

 and having a slightly-marked mid-rib and 

 rootlets. And suppose that, as shown, 

 a secondary frond is proliferously pro 

 duced from the mid-rib, and continues 

 attached to it. Evidently the ordinary dis 

 continuous development, can thus become 

 a continuous development, only on con 

 dition that there is an adequate supply, 

 to the secondary frond, of such materials 

 as are furnished by the rootlets: the re 

 maining materials being obtainable by 

 itself from the air. Hence, that portion of 

 the mid-rib lying between the secondary 

 frond and the chief rootlets, having its function increased, 

 will increase in bulk. An additional consequence will be a 

 greater concentration of the rootlets there will be extra 

 growth of those which are most serviceably placed. Observe, 



