FORMATION OF SPONGIOLES IN FLOWERING- PLANTS. 



same plan with the branches above. Moreover, it will be seen 

 that, from the sides and extremities of these underground branches, 

 there proceed a number of delicate fibres ; and if the extremities 

 of these be carefully examined, they will be found to be much 

 softer than the rest of the structure. Now these fibrils are the 

 true roots ; and their soft succulent extremities, which are called 

 spongioles, are the parts by which alone they absorb or suck up 

 fluid. This is easily proved. If a growing Radish be carefully 

 removed from the ground, and the fleshy portion be bent in such 

 a manner, that it can be covered with water, whilst the leaves 

 and the tuft of fibres at the point of the root are not immersed, 

 it will be found that the whole of this large surface does not 

 absorb moisture enough, to keep the plant alive. But, on the 

 other hand, if this tuft of fibres be only so far immersed in the 

 water, that their points may touch it, whilst the rest of the root 

 is above the surface, the plant will continue to flourish. 



105. The fact is, that this absorption takes place with the 

 greatest rapidity, through soft newly-forming tissue ; and this is 

 what gives the spougioles their peculiar power. They are, indeed, 

 simply the growing points of the rootlets, which are constantly 

 increasing in length, and which in this manner go in search, as 

 it were, of the supplies of food, of which they have exhausted the 

 soil that previously covered their extremities. As this growth 

 continues, the tissue at first formed gradually becomes con- 

 solidated ; and when it has become hardened, it is no longer 

 adapted for absorption in more than a very trifling degree ; so 

 that, to the newly-forming point of the fibre, this power is 

 always nearly restricted. But in the young plant, there is an 

 interesting correspondence with the condition of the lower 

 tribes; for the soft roots, which are first sent down from the 

 seed, when it is commencing to grow or germinate, are, like the 

 fibres proceeding from the base of the Mushroom-stem, capable 

 of absorbing by their whole surface ; and it is only when woody 

 fibre begins to be formed in them, that the power is restricted to 

 their extremities. 



106. The knowledge that the delicate fibres, proceeding from 

 what are commonly known as roots, are the true and only organs 



