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Some B^aptation of Mater plantd to 

 tbeir lEnvironment. 



By W. Falconer. 



WATER plays such an all-important part in the growth and 

 economy of every organism that no surprise is felt either 

 at the abundance or variety of vegetable life found in 

 moist situations ; and when we note the habitats selected by the 

 various plants, the banks clothed with flowers, grasses, and sedges 

 in tangled confusion, the shallow waters of the edge in which grow 

 many familiar floral' types, and the deeper central waters in which 

 other forms flourish, and note, also, the conditions under which 

 they grow, so diverse and so different to those which obtain in the 

 case of land-plants, one naturally expects much differentiation of 

 structure due to environment, and the acquisition of new habits 

 to meet the altered circumstances under which each must perfect 

 its seed, reproduce its kind, and obtain the air and light necessary 

 to a healthy and continued existence. Nor is our expectation 

 disappointed, and in pursuing our inquiries into the subject it 

 becomes a matter of some difficulty to select from the wealth of 

 material at our disposal typical exemplifications of the now 

 accepted principles of scientific investigation, inaugurated by 

 Darwin and Wallace. I propose, within the limits of the space 

 allotted to this paper, to deal with a few characteristic adaptations 

 of water-plants to their surroundings which are of general interest. 

 I. — We observe in them a deficiency as well as a different 

 arrangement of the strengthening or woody tissue, which gives 

 mechanical support to stems and other structures. In a land- 

 plant, the bundles of this material are arranged towards the peri- 

 phery of the stem, in which position they are most advantageously 

 disposed to withstand the varied and constant strains to which 

 they are exposed, and which are mainly lateral, arising chiefly from 

 the action of winds which blow in a lateral direction. The 

 organism has, by this provision of nature, sufficient strength in 

 itself to endure the strife of the elements, and so escapes destruc- 

 tion. By way of illustration, and from the point of view of an 

 engineer, we might compare the plant to the cylindrical iron sup- 



