18681874] EXPRESS!! ON 105 



and dilates under passions, independently of the amount of Letter 470 

 light Can you give any explanation of this statement ? 

 When the heart beats hard and quick, and the head becomes 

 somewhat congested with blood in any illness, does the pupil 

 contract? Does the pupil dilate in incipient faintness, or in 

 utter prostration, as when after a severe race a man is pallid, 

 bathed in perspiration, with all his muscles quivering ? Or in 

 extreme prostration from any illness? 



To W. Turner. Letter 471 



Down, March 28th [1871]. 



I am much obliged for your kind note, and especially for 

 your offer of sending me some time corrections, for which I 

 shall be truly grateful. I know that there are many blunders 

 to which I am very liable. There is a terrible one confusing 

 the supra-condyloid foramen with another one. 1 This, how- 

 ever, I have corrected in all the copies struck off after the first 

 lot of 2500. I daresay there will be a new edition in the 

 course of nine months or a year, and this I will correct as 

 well as I can. As yet the publishers have kept up type, and 

 grumble dreadfully if I make heavy corrections. I am very 

 far from surprised that "you have not committed yourself to 

 full acceptation " of the evolution of man. Difficulties and 

 objections there undoubtedly are, enough and to spare, to 

 stagger any cautious man who has much knowledge like 

 yourself. 



I am now at work at my hobby-horse essay on Expression, 

 and I have been reading some old notes of yours. In one 

 you say it is easy to see that the spines of the hedgehog are 

 moved by the voluntary panniculus. Now, can you tell me 

 whether each spine has likewise an oblique unstriped or 



1 In the first edition of the Descent of Man, I., p. 28, in quoting Mr. 

 Busk " On the Caves of Gibraltar," Mr. Darwin confuses together the 

 inter-condyloid foramen in the humerus with the supra-condyloid foramen. 

 His attention was called to the mistake by Sir William Turner, to whom 

 he had been previously indebted for other information on the anatomy 

 of man. The error is one, as Sir William Turner points out in a letter, 

 " which might easily arise where the writer is not minutely acquainted 

 with human anatomy." In speaking of his correspondence with 

 Darwin, Sir William remarks on a characteristic of Darwin's method of 

 asking for information, namely, his care in avoiding leading questions. 



