174 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 



XXIII. 



THE EXTERNAL CONFIGURATION OF 

 PLANTS IN RELATION TO WIND PRES- 

 SURE AND WATER CURRENTS. 



BY ALEX. S. WILSON, M.A., B.SC. 



[Read 28th April, 1885.] 



Notwithstanding the infinite variety of vegetable 

 life, the bodily shapes of plants are not without 

 their significance. The correspondence between a 

 X)lant's external configuration and its environment, 

 although recognised by all in a general way, is not 

 usually held to extend very far. The shapes of 

 organic beings in many instances are so strange as 

 to give the inijDression of arbitrariness ; and even 

 naturalists are prone to ascribe them to the influ- 

 ences of heredity and variation, or whatever un- 

 known agencies these terms may cover. As 

 knowledge advances, however, the forms of living 

 things must become more and more intelligible, and 

 the correspondence between organ and environment 

 be traced further and further into the details of 

 shape and structure. No one can fail to remark 

 the way in which the bodies of animals are adapted 

 to the medium in which they live, — a bird's body, 

 for instance, is fashioned in correspondence with 

 tlie air through which it moves, — the external form 

 of a fish is related to its aquatic existence, while 

 the shape of a land animal is determined in relation 

 to the atmosphere it breathes and to the earth's 

 surface which it treads. The adjustment of organic 

 forms to their immediate surroundings often fails 

 to impress us, from our habitually taking for 

 granted the existence of such a relationship. We 

 become sensible of its extent and importance when 

 n transposition takes place, as when a land animal 



