10 



FERNS IN THEIR HOMES AND OURS. 



increases from within, and is continually worn 

 away on the outside as it is pushed ahead by the 

 lengthening of the root. The lightest portion of 

 the figure marked b c represents the true root ; and 

 the longitudinal growth takes place between the 

 points b and r, this portion being the only part of 

 the root capable of absorbing much nourishment. 

 This absorption occurs through the outer cells and 

 root-hairs. The darker parts of the roots do not 

 continue to lengthen, — a fact obvious after a 

 moment's thought ; as, if they did, the whole mass 

 of roots would become tangled and knotted, and 

 healthy circulation made impossible for the matter 

 which is absorbed at the tips. Now, it will be 

 seen how injurious it must be to roughly tear up, 

 or pull to pieces, the mass of roots, when we are 

 removing or transplanting ferns. These remarks 

 may be applied as well to other plants ; for it can 

 be understood that if the only living portion of 

 the root, so to speak, be torn off, the plant is 

 again reduced to the condition of an ordinary 

 fresh cutting, which has again to go through the 

 process of forming roots. The two extreme forms 

 of the stem, or rhizome, in ferns, may be illustrat- 

 ed by Pteris aqtnlina (PI. 5, Fig. 10) and any tree- 

 fern (PI. 7). The former apparently throws up 

 its fronds here and there separately from some 

 invisible point : the latter regularly unfolds its 

 crown from immediately within the circle of fronds 

 last unfolded. 



