1893 ENVIEONMENT ON PLANT STRUCTURES 327 



I am -^Titing this in great haste. I trust that 

 you are enjoying Costebelle. 



Very truly yours, 



T. BuBDON Sandebson. 



At this time Mr. Komanes had a very interesting 

 correspondence with the Eev. G. Henslow, on the 

 subject of the direct action of the environment on 

 plant structures. 



Ealing : October 19, 1893. 



Dear Mr. Romanes, — If you are in town on 

 November 16, I should be very glad indeed if you 

 could come to the Linnean Society, and criticise my 

 paper which I am going to read : ' On the origin of 

 plant structures by self-adaptation to the environ- 

 ment, exemplified by desert and xerophyllous plants.' 



In this and in subsequent letters Mr. Henslow 

 explained the subject-matter of his paper, and as 

 it formed the basis of the correspondence, a brief 

 analysis, furnished by Mr. Henslow in a later letter, 

 is here inserted. 



The object of the paper is to show that the origin 

 of varieties and species — as far as the vegetative 

 organs are concerned — is solely due to climatic 

 causes. Por the acquired (somatic) characters be- 

 come more or less hereditary if the same environ- 

 ment be maintained. But plants possess every de- 

 gree in their capacities either of reverting, changing, 

 or of stahilitij. 



The result is that I do not see any necessity for 



