440 LETTERS TO 'DARWIN, 1843-1859 



I cannot prove that there is much hybridising l in nature, 

 but do not see why there should not be, as we do not doubt 

 that species require the pollen of other individuals, exactly 

 as in the higher animals you must not ' breed in ' (I think the 

 term is). 



I cannot hook my Kerguelen trees or climate on to the 

 vacillating temperature of S. America : many thanks for 

 the information though. Do you connect the union of the 

 Conchogeographic districts at the Galapagos with the 

 currents ? 



Every young Irish Yew bears berries ; there is a sort of 

 Irish Yew in Ayrshire which I believe, like the Goddess 

 Diana of the Ephesians, dropped down from Heaven, and 

 picked itself up in a garden ; when I hear whether it bears 

 berries I will tell you if she be equally chaste. If the Yew 

 had been Italian and bows made it would have been dedi- 

 cated to Diana. 



And now to bother you for the last time. The re-appear- 

 ance of plants in certain situations is a curious phenomenon 

 of which instances are multiplying daily in this neighbour- 

 hood : there are doubtless series of seeds in some grounds 

 lying dormant but not dead : what a curious principle life 

 must be and what an uncomfortable abode it must often have. 

 Cutting open railways causes a change of vegetation in two 

 ways, by turning up buried live seeds and by affording space 

 and protection for the growth of transported seeds : so that 

 it is often very difficult to determine to which cause the 

 appearance or superabundance of a plant is attributable. 

 The Dutch Clover case is constantly quoted, but the Stirling 

 Castle one is more curious. The King's Park was dug up in 

 about 1650 ? during the 1st rebellion ; wherever the cuts were 

 made for encampments, the Broom appeared, but in a year 

 or two disappeared. In the rebellion of 1745, it was again 

 encamped upon and again Broom came up and disappeared : 

 it was afterwards ploughed and immediately became covered 

 with Broom, which has all, for the third time, vanished. 



To conclude (I have been reading Scotch Sermons !) 

 how curious that water plants should be so widely dif- 

 fused. Water must have been a mighty agent in dissemina- 

 tion ; not only though are these diffused but are diffusable. 



1 The word is used in the sense of the later ' cross-fertilisation.' 



