Vegetable Physiology. 151 



roots, to form future trunks. The space which 

 nangi"& t t * 



• overed was so large that it was estimated that seven 



, usan d persons might find room beneath its shade. Milton 



, me ntioned this remarkable tree in the following lines : 



"The fig tree ; not that kind for fruit renowned ; 

 But such as at this day to Indians known, 

 In Malabar or Deccan, spreads her arms, 

 Branching so broad and long, that in the ground 

 The bending twigs take root, and daughters grow 

 About the mother tree, a pillared shade, 

 High over arched, with echoing walks between." 



The Tree Ferns of tropical countries are the only flowerless 

 plants w hich form true woody trunks. The stems of these 

 are sometimes hollow, and sometimes contain a kind of pith. 

 Their mode of growth differs from that of either Exogens or 

 Endo^ens. When cut across, the stem is seen to consist of a 

 number of hard woody plates, adhering rather loosely together, 

 and these are found to be either continuations of the flat- 

 tened footstalks of the leaves which crown the summit, or the 

 remains of those which have dropped off. Each year the 

 leaves fall off, and are replaced by a new set, formed above, 

 so that the stem goes on increasing in length, but very little 

 in diameter. It is generally the case in these and other cryp- 

 togamia, that the portions first produced undergo little change, 

 and hence such plants have received the name of Acrogens, 

 which signifies growth by the point, or by addition to the ex- 

 tremities alone. 



