• 



• 



XIII 



The Uses and Origin of the Arrangements of leans in Plants 



BY CHAUNCEY WRIGHT. 



Communicated October 10, 1871. 



In proposing to treat in this paper of the origin of some of the more common 

 arrangements of leaves and leaf-like organs in the higher orders of plants, 1 do 



on. but 



pi p 



<»< 



not intend to make this question the principal object of discusi 

 only to consider it so far as it affords useful hypotheses for the im rpietotion of 

 some of the obscurer features- in the main object of this inquiry namely, 

 questions of the uses of these arrangements, or of their adaptations to the 



vard economy of the plant's life, and to the conditions of its existen* 

 such a discussion 



If 



que 



ission hypothesis can be made to throw light on physiological 

 while seeking more directly to connect in a continuous series tin 



simpler and more general with the more specific and compln-.-ited forms in veg 



life 



will gain for itself a much greater interest and value th 



it would 



therw 



possess 



It 



indeed, in this value of the principle of Natural Sele< 



tion, its value and use as a working hypothesis 

 respect consists. If any subsidiary hypothesis unde 



the 



l principal claim to 

 eory serve only II a 



principle of connection, a thread on which we may arrange and more clear! \ 



of 



regard relationships that are the objects 

 it wiil at least serve a useful purpose, and 



more promising scientific mqui 



bility to the theory in general of the 



of their utilities, or through 

 of life. 



even, perhaps, give greater plau& 



>f organic forms through the agency 



the advantages these have given to surviving forms 



There is hardly any animal or 



plant, especially of the higher orders, th 



has 



not in many of the characteristics of i 

 to the outward conditions of its life 

 world," or at least to the many values 



structure very conspicuous 



lap tat 



to 



« the 



part it has to play in 



the 



or 



advantages it has to cure 



This fact 



has led many naturalist., whose opinion, until lately, and for a long time, ha. 



prevailed, to re 

 subordinate -par 



■5 



d a 



living structure as principally, 



if 



entirely, made up of 



or 



gans 



which exist for specific purposes, or are essentially 



