18431862] KNIGHT'S LAW 251 



that some unknown causes had favoured development of trees Letter 583 

 and bushes in New Zealand, and consequent on this there 

 had been a development of separation of sexes to prevent 

 too much intermarriage. I do not, of course, suppose the 

 prevention of too much intermarriage the only good of 

 separation of sexes. But such wild notions are not worth 

 troubling you with the reading of. 



To J. D. Hooker. Letter 



Moor Park [May 2nd, 1857]. 



The most striking case, which I have stumbled on, on 

 apparent, but false relation of structure of plants to climate, 

 seems to be Meyer and Doege's remark that there is not one 

 single, even moderately-sized, family at the Cape of Good 

 Hope which has not one or several species with heath-like 

 foliage ; and when \ve consider this together with the number 

 of true heaths, any one would have been justified, had it not 

 been for our own British heaths, 1 in saying that heath-like 

 foliage must stand in direct relation to a dry and moderately 

 warm climate. Does this not strike you as a good case of 

 false relation ? I am so pleased with this place and the 

 people here, that I am greatly tempted to bring Etty here, for 

 she has not, on the whole, derived any benefit from Hastings. 

 With thanks for your never failing assistance to me . . . 



I remember that you were surprised at number of seeds 

 germinating in pond mud. I tried a fourth pond, and took 

 about as much mud (rather more than in former case) as 

 would fill a very large breakfast cup, and before I had left 

 home 118 plants had come up; how many more will be up 

 on my return I know not. This bears on chance of birds by 

 their muddy feet transporting fresh-water plants. 



This would not be a bad dodge for a collector in country 

 when plants were not in seed, to collect and dry mud from 

 ponds. 



1 It is well known that plants with xerophytic characteristics are not 

 confined to dry climates ; it is only necessary to mention halophytes, 

 alpine plants and certain epiphytes. The heaths of Northern Europe 

 are placed among the xerophytes by Warming (Lehrbuch der bkofagischen 

 Pflanzengeographie, p. 234, Berlin, 1896). 



