440 LETTERS TO DARWIN, 1843-1859 
I cannot prove that there is much hybridising ^ 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 3^ou 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 equaity chaste. If the Yew 
had been Itahan 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 : wdiat 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 Stirhng 
Castle one is more curious. The King's Park was dug up in 
about 1650 ? dming 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 v>'as 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 1) 
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. 
^ The word is used in the sense of the later ' cross-fertilisation.' 
