NOTES ON BOTANY. 49 



for mentioning it in this connexion. At any rate, we have here a 

 very interesting question. It has generally been held that all 

 individuals of the same species possess a common ancestry, the 

 chances against the same form being independently evolved in two 

 or more places being supposed to be indefinitely small. But why 

 should not the same parent-species under similar or nearly identical 

 conditions vary in the same way at more than one time ? Long 

 ago (if I remember aright) Professor Mivart argued in favour of 

 this conclusion in the case of certain freshwater fishes, and, after 

 all, the question of probability may be answered in more than one 

 way. Xo doubt the chances are very small, yet from an indefinitely 

 large number of opportunities the most unlikely results may be 

 expected, though rarely. 



In Hieracium it seems not unlikely that Mr. F. J. Hanbury's 

 Scottish researches may result in the establishment of some 

 endemic forms ; but neither Hiemcia nor Rubi can claim undoubted 

 specific rank. Both genera (at least those sections with which we 

 are concerned) would seem to be at present in a most unstable 

 condition. Sub-species abound, but sharply defined species can 

 hardly be found. 



There is still one plant, which may possibly claim a purely 

 British origin. I mean Arabis ciliata, R. Br., a very rare species 

 found in Clare and Galway, and also reported formerly from 

 Pembrokeshire. I do not know it all well, but it seems to me 

 fairly distinct from any form of the common A. sagittata, D.C., 

 and also from the continental A. alpestris, Schleich., with which it 

 has sometimes been identified. Yet Hooker does not consider it 

 more than a sub-species of A. sagittata. It will now, I think, be 

 acknowledged, that our endemic forms are, to say the least, very 

 limited in number and somewhat doubtful in quality. 



Returning to the main question, it is well known that the late 

 Edward Forbes considered our existing Flora as being composed of 

 five distinct elements. What we may call our ordinary Flora is 

 markedly Germanic in its type i.e., our common plants are 

 identical with species indigenous to Germany and the neighbouring 



