DARWIN MEMORIAL. 73 



He gave reasons for the belief (now generally accepted) that the 

 usual gaudy coloring of intertropical insects is not related either to 

 the heat or light of those zones, but rather to the conditions of ex- 

 istence being generally favorable to life. — (Journal of Researches, 

 etc., p. 381.) He has written on the Phosphorescence of Fire-flies, 

 and on the habits of the larva of one of them — Lamphyris occidentalis. 

 — {Ibid, pp. 29-30.) He discussed the food-habits of stercovorous 

 beetles, with reference to the origination of a new habit and the 

 power of adaptation to new conditions. — {Ibid, p. 490, note.) 



At Port St. Julian, Patagonia, he found a species of Tabanus 

 extremely common, and remarks: "We here have the puzzle that 

 so frequently occurs in the case of mosquitoes — on the blood of 

 what do these insects commonly feed? The guanaco is nearly the 

 only warm-blooded quadruped, and is found in quite inconsiderable 

 numbers compared with the multitude of flies." He has discussed 

 the question of hibernation of insects, and shown that it is governed 

 by the usual climate of a district, and not by absolute temperature. 

 {Ibid, 98-9.) He gave the first true explanation of the springing 

 power of the Elateridae when laid on their backs, showing how 

 much depended on the elasticity of the sternal spine. {Ibid, p. 31.) 

 He was the first, I believe, to record the exceptional powers of run- 

 ning and of making sound, in a butterfly, viz., Ageronia feronia of 

 Brazil. 



In his most famous work he lays stress particularly on the follow- 

 ing facts and generalizations, for which he draws from insects : the 

 individual differences in important characters; the remarkable 

 manner in which individuals of the same brood often differ, dimor- 

 phism and trimorphism being only the extreme exaggeration of 

 this fact ; the difficulty of distinguishing between species and varie- 

 ties; that geographical races are local forms completely fixed and 

 isolated ; that representative species are better distinguished from 

 each other than local forms and sub-species ; that the species of 

 large genera vary more frequently than those of small genera, and 

 that specific differences in the former are often exceedingly small ; 



