OUTLINE OF THE YORK ADDRESS 223 



sphere, not only were they paralleled in the Southern, and 

 from similar causes, but the work of Saporta and Dyer had 

 gone on to make it probable that all plant life had originated 

 in the polar regions, and radiated thence to be differentiated 

 in different regions. 



Kew : August 4, 1881. 



DEAE DARWIN, I am groaning over my Address for 

 York after a fashion with which I have more than once bored 

 you awfully. Now do believe me when I say that 'it is an 

 unspeakable relief to me to groan towards you ; and I 

 will have clone. 



I am trying to formulate my ideas- on the subject of the 

 several stages or discoveries or ideas by which the Geog. 

 Distrib. (of plants) has been brought up to be a science 

 and to its present level, and showing that these stages have 

 all been erected on ideas first entertained by great voyagers 

 or travellers, thus ' hitching ' myself on to the sympathies 

 of a geographical audience ! something in this following 

 sort of way : 



1. Tournefort's enunciation of the likeness between the 

 vegetation of successive elevations and degrees of latitude : 

 the true bearings of which have come out only now that we 

 know that said vegetations are affiliated in fact as well as in 

 appearance. 



2. Humboldt's showing that great Natural Orders, 

 Gramineae, Leguminosae, Compositae, &c., are subject to 

 certain laws of increase or decrease relatively to other plants, 

 in going polewards (in both hemispheres) and skywards. 

 I should also refer parenthetically to his construction of the 

 isothermals as so great an engine towards the advancement 

 of Geog. Bot. 



Now will you give me your idea as to whether I should be 

 right in calling Humboldt the greatest of scientific travellers, 

 or only the most accomplished, or most prolific ? It is 

 the custom to disparage Humboldt now as a shallow man, 

 but when I think of what he did through his own observa- 

 tions during travel, for Geographical distribution of plants, 

 for Meteorology, for Magnetism, for Topography, for Physical 

 Geography and Hydrography, for Ethnology, for political 

 history of Spanish America and for Antiquity of Mexico 



