1 857.] WATER-CURE. 91 



the same laws as recognised and admitted varieties. I mention 

 all this on account of the variation of plants in ascending 

 mountains ; I have quoted the foregoing remark only generally 

 with no examples, for I add, there is so much doubt and dispute 

 what to call varieties ; but yet I have stumbled on so many 

 casual remarks on varieties of plants on mountains being so 

 characterised, that I presume there is some truth in it. What 

 think you-? Do you believe there is any tendency in varieties, 

 as generally so called, of plants to become more hairy, and 

 with proportionally larger and brighter-coloured flowers in 

 ascending a mountain ? 



I have been interested in my " weed garden," of 3 X 2 feet 

 square : I mark each seedling as it appears, and I am 

 astonished at the number that come up, and still more at 

 the number killed by slugs, &c. Already 59 have been so 

 killed ; I expected a good many, but I had fancied that this 

 was a less potent check than it seems to be, and I attributed 

 almost exclusively to mere choking, the destruction of the 

 seedlings. Grass-seedlings seem to suffer much less than 

 exogens. . . . 



C. Darwin to y. D. Hooker. 



Moor Park, Farnham, [April (?) 1857.] 



MY DEAR HOOKER, Your letter has been forwarded to 

 me here, where I am undergoing hydropathy for a fortnight, 

 having been here a week, and having already received an 

 amount of good which is quite incredible to myself and quite 

 unaccountable. I can walk and eat like a hearty Christian, 

 and even my nights are good. I cannot in the least under- 

 stand how hydropathy can act as it certainly does on me. 

 It dulls one's brain splendidly ; I have not thought about 

 a single species of any kind since leaving home. Your note 

 has taken me aback ; I thought the hairiness, &c., of Alpine 

 species was generally admitted ; I am sure I have seen it 



