1843-1882] GLACIAL PERIOD 473 



the Cameroons, and as Seemann describes, in low mountains Letter 359 

 of Panama. It is, as you say, absurd to suppose that such 

 a genus as Dipterocarpus^ could have been developed since 

 the Glacial era ; but do you feel so sure, as to oppose 2 a 

 large body of considerations on the other side, that this 

 genus could not have been slowly accustomed to a cooler 

 climate? I see Lindley says it has not been brought to 

 England, and so could not have been tried in the green- 

 house. Have you materials to show to what little height 

 it ever ascends the mountains of Java or Sumatra? It 

 makes a mighty difference, the whole area being cooled ; 

 and the area perhaps not being in all respects, such as 

 dampness, etc., etc., fitted for such temperate plants as 

 could get in. But, anyhow, I am ready to swear again that 

 Dipterocarpus and any other genus you like to name did 

 survive during a cooler period. 



About reversion you express just what I mean. I 

 somehow blundered, and mentally took literally that the 

 child inherited from his grandfather. This view of latency 

 collates a lot of facts secondary sexual characters in 

 each individual ; tendency of latent character to appear 

 temporarily in youth ; effect of crossing in educing talent, 

 character, etc. When one thinks of a latent character 

 being handed down, hidden for a thousand or ten thousand 

 generations, and then suddenly appearing, one is quite 

 bewildered at the host of characters written in invisible 

 ink on the p-erm. I have no evidence of the reversion 



o 



of all characters in a variety. I quite agree to what 

 you say about genius. I told Lyell that passage made 



me groan. 



What a pity about Falconer ! 3 How singular and how 

 lamentable ! 



Remember orchid pods. I have a passion to grow the 

 seeds (and other motives). I have not a fact to go on, but 

 have a notion (no, I have a firm conviction !) that they are 



1 Dipterocarpus, a genus of the Dipterocarpaceas, a family of dicoty- 

 ledonous plants restricted to the tropics of the Old World. 



2 The meaning seems to be : "Do you feel so sure that you can bring 

 in opposition a large body of considerations to show, etc." 



3 This refers to Falconer's claim of priority against Lyell. See Life 

 and Letters, III., p. 14 ; also Letters 166 and 168. 



