64 EVOLUTION [CHAP. II 



Letter 27 churchyard without the problem be solved by some one 

 before I die. Talking of dying makes me tell you that my 

 confounded stomach is much the same ; indeed, of late has 

 been rather worse, but for the last year, I think, I have been 

 able to do more work. I have done nothing besides the 

 barnacles, except, indeed, a little theoretical paper on erratic 

 boulders, 1 and Scientific Geological Instructions for the 

 Admiralty Volume, 2 which cost me some trouble. This work, 

 which is edited by Sir J. Herschel, is a very good job, inas- 

 much as the captains of men-of-war will now see that the 

 Admiralty cares for science, and so will favour naturalists on 

 board. As for a man who is not scientific by nature, I do 

 not believe instructions will do him any good ; and if he be 

 scientific and good for anything the instructions will be 

 superfluous. I do not know who does the Botany ; Owen 

 does the Zoology, and I have sent him an account of my new 

 simple microscope, which I consider perfect, even better than 

 yours by Chevalier. N.B. I have got a J" object-glass, and 

 it is grand. I have been getting on well with my beloved 

 Cirripedia, and get more skilful in dissection. I have worked 

 out the nervous system pretty well in several genera, and 

 made out their ears and nostrils, 3 which were quite unknown. 

 I have lately got a bisexual cirripede, the male being micro- 

 scopically small and parasitic within the sack of the female. I 

 tell you this to boast of my species theory, for the nearest 

 closely allied genus to it is, as usual, hermaphrodite, but I had 

 observed some minute parasites adhering to it, and these 



1 " On the Transportal of Erratic Boulders from a Lower to a Higher 

 Level" (Quart. Journ. GeoL Soc., Vol. IV., pp. 315-23. 1848). In this 

 paper Darwin favours the view that the transport of boulders was effected 

 by coast-ice. An earlier paper entitled " Notes on the Effects produced 

 by the ancient Glaciers of Caernarvonshire, and on the Boulders trans- 

 ported by floating Ice" (Phil, Mag. 1842, p. 352) is spoken of by Sir 

 Archibald Geikie as standing "almost at the top of the long list of 

 English contributions to the history of the Ice Age" (Charles Darwin, 

 Nature Series, p. 23). 



' 2 A Manual of Scientific Enquiry, prepared for the use of Her 

 Majesty's Navy, and adapted for Travellers in General. Edited by Sir 

 John F. W. Herschel, Bart. Section VI. Geology by Charles Darwin. 

 London, 1849. See Life and Letters, pp. 328-9. 



3 For the olfactory sacs see Darwin's Monograph of the Cirripedia, 

 1851, p. 52. 



