54 PLANT LIFE 



photosynthesis; whilst it has overcome the 

 disabilities apparently inherent in its type 

 of organisation, by strengthening and cement- 

 ing together the branching filaments, of which 

 it is built up, by means of the calcium car- 

 bonate which it withdraws from the sea-water. 



The consideration of the noncellular or 

 syncytial plant has been introduced in order 

 to illustrate the varieties of one possible 

 type of structure. Save, however, for the 

 production of a few aquatic representatives 

 it does not mark a line of important advance. 

 The multicellular condition contained within 

 itself the promise of the future, and it is as 

 multicellular organisms that the higher plants 

 have been evolved. 



It will be useful at this point to sum up the 

 salient points of the preceding discussion, 

 so as to gain a clear starting-point from which 

 to study the evolution and modification of 

 form and structure in the higher terrestrial 

 forms of life. 



We have seen the striking consequences 

 which accrue from the possession of an invest- 

 ing membrane in their effects upon the mode of 

 nutrition, and indirectly upon other functions, 

 e. g. that of motility, in plants. We have learnt 

 in the relatively lowly members of the vege- 

 table kingdom which have been passed under 

 review, why a need for the presentation of 

 the green surfaces to light should be a matter 

 of such cardinal importance as to dominate 

 the organisation of every one of them. We 



