The Ohio VS(^aturalist, 



PUBLISHED BY 



The Biological Club of the Ohio State Uni'versity. 



Volume XIV. FEBRUARY, 1914. No. 4. 



TABLE OF CONTENTS. 



Dachnowski— Transpiration in Relation to Growtii and to tlie Snccessional and 



Geographic Distribution of Plants 241 



Drake— An Occurence of Atypus Milberti Walck. in Ohio 251 



Napper— Flood Erosion Along Paint Creek, Fayette County, Ohio 252 



ScHAEFNER— Ecological Varieties as Illustrated by Salix Interior 255 



TRANSPIRATION IN RELATION TO GROWTH AND TO THE 

 SUCCESSIONAL AND GEOGRAPHIC DISTRIBUTION 



OF PLANTS.* 



Alfred Dachnowski. 



In former publications (Botanical Gazette 49; 325-339, 1910; 

 Ibid 54; 503-514; Bulletin 16, Geological Survey of Ohio, 1912) 

 the writer invited a closer consideration of a number of points 

 of interest to students of modem phases of Botany. Among 

 other matters, attention was called to the fact that while the 

 presence of structural modifications is generally regarded as a 

 condition in favor of certain plants which are limited to habitats 

 favorable to them, the more noteworthy characteristic is very 

 likely functional variability, when plants extend the areal range 

 beyond their typical habitats. It is a well known fact that 

 plant migrations are not completed as yet, and that vegetational 

 limits are determined more frequently by developmental than 

 by climatic or edaphic conditions. European ecologists especially 

 have furnished notable instances of this character, and the more 

 important results of the several International Phytogeographic 

 excursions into various parts of the world tend to give prominence 

 to the problem of functional plasticity in plants of the same 

 species, but of ecologically and geographically separate regions. 

 Relative power of endurance and acclimatization are questions 

 of special significance also in the existing peculiarities of scattered 

 geographical distribution as well as in physiological ecology. 



* Contribution from the Botanical Laboratory of Ohio State University, 

 No. 80. 



241 



