^90 



THE NATUKALIST. 



iated vegetable forms, at present distinct, hereditary, irreducible, by ouir 

 means of experiment ; tbe second, that amongst these related forms, the most 

 closely related are those which grow spontaneously in the same places and 

 under conditions of existence altogether identical. 



You take due notice of the first of these two facts ; as to the second you 

 pass it over in silence, and in such a manner, that your reader, without 

 otherwise knowing the state of the question, would arrive at a very inexact 

 idea, and would find nothing improbable in the hypothesis advanced by you, 

 according to which the greater part of the allied species, which I have indi- 

 cated, are very probably only stationed varieties of one and the same type 

 due to different conditions of existence, and which have acquired, during 

 the lapse of centuries, a constancy, if not absolute, at least relative, in their 

 distinctive characters. Whereas this very hypothesis falls of itself, and 

 cannot be sustained if considered as an actual fact, and also upon what I 

 have afi&rnied that those species truly most related, are ordinarily social 

 species. It is necessary then to seek for another explanation of their existence. 

 We ask, how have these forms which grow spontaneously, pele-mele, shewing 

 themselves hereditary and unchangeable, been able to produce and fix them- 

 selves, if they are only varieties springing from one common type, the slight 

 but constant differences which separate them not being attributable to any 

 local influences 1 



A simple and very natural explanation, which presents itself to the 

 mind at first sight, is, to admit the original diversity of permanent closely 

 allied forms, as specific types ; the one which I. have adopted because it 

 appeared to me impossible to find another of any value, and it is 

 besides so fully satisfactory to reason. One cannot indeed conceive how 

 the forms, which under our very eyes, do 7iot vary, and in which no appreci- 

 able external cause has previously been sufficient to cause variation, should 

 nevertheless be but varieties produced by the same type. 



If we afterwards compare other allied forms, equally permanent, but 

 placed in different situations, and if we ascertain that their differences are 

 equal, or even superior, in importance to those which separate the social alKed 

 forms ; is it possible to attribute these differences to the sole influence of 

 situation 1 When the true measure of possible affinity of species is presented 

 to us by the social forms, which we are forced to consider as specific types, 

 can we reasonably admit that there exist in nature, in a wild state, simple 

 varieties purely stational, the characters of v/liich are often more important 

 than, and always as constant as, those of true species. 



