ROOT. 13 



Plants have the power of replacing spongioles 

 by the formation of new ones ; so that an in- 

 dividual is not destroyed by their loss. 



But this power depends upon the coopera- 

 tion of the atmosphere, and upon the special 

 vital powers of the species. 



If the atmosphere is so humid as to hinder 

 evaporation from the leaves, spongioles will 

 have time to form anew ; but if the atmosphere 

 is dry, the loss by evaporation will be so much 

 greater than can be supplied by the injured 

 roots, that the whole plant will be emptied of 

 fluid before the new spongioles can form, and 

 death will ensue. 



This is the key to the operations of trans- 

 plantation and propagation by cuttings scions 

 and buds. 



As roots are destitue of leaf-buds, and as 

 leaf-buds are essential to the multiplication of 

 an individual, it should follow that roots can 

 never be employed for the purpose of multipli- 

 cation. 



Nevertheless, roots have, occasionally, the 

 power of generating leaf-buds, which being 

 latent, and not according to the usual operations 

 of nature, are called adventitious; and when 

 this is the case, they may be employed for the 

 2 



