348 LAWS OF VARIATION. Char XXVI 



from 



« ^ Se6 f, S situated in this Portion of the pod, give eighty per cent, of single 

 ' flowers." Now the production of single-flowering plants from the seed of 

 double-flowering plants is clearly a case of reversion. These latter facts, 

 as well as the connection between a central position and pelorism and 

 prolitication, show m an interesting manner how small a difference -namely 

 a little greater freedom in the flow of sap towards one part of the same 



plant 



Analogous or Parallel Variation.— By this term I wish to 

 express that similar characters occasionally make their appear- 

 ance in the several varieties or races descended from the same 

 species, and more rarely in the offspring of widely distinct species. 

 We are here concerned, not as hitherto with the causes of varia- 

 tion, but with the results ; but this discussion could not have 

 been more conveniently introduced elsewhere. The cases of 



analog 



6 acted on organic t 



ms variation, as tar as their origin is concerned, may b 

 ped, disregarding minor subdivisions, under two main heads 

 firstly, those due to unknown causes havii 

 beings with nearly the same constitution, and which consequently 

 vary in an analogous manner ; and secondly, those due to the 

 reappearance of characters which were possessed by a more 

 or less remote progenitor. But these two main divisions can 

 often be only conjecturally separated, and graduate, as we shall 

 presently see, into each other. 



Under the first head of analogous variations, not due to reversion we 

 have the many cases of trees belonging to quite different orders which 

 have produced pendulous and fastigate varieties. The beech, hazel, and 

 barberry have given rise to purple-leaved varieties; and as Bernhardi 

 has remarked/ 8 a multitude of plants, as distinct as possible, have yielded 

 varieties with deeply-cut or laciniated leaves. Varieties descended from 

 three distinct species of Brassica have their stems, or so-called roots en- 

 larged into globular masses. The nectarine is the offspring of the peach ; 

 and the varieties of both these trees offer a remarkable parallelism in the 

 fruit being white, red, or yellow fleshed— in being clingstones or free- 

 stones—in the flowers being large or small— in the leaves being serrated 

 or crenated, furnished with globose or reniform glands, or quite destitute 

 of glands. It should be remarked that each variety of the nectarine has 

 not derived its character from a corresponding variety of the peach. The 

 several varieties also of a closely allied genus, namely the apricot, differ 

 from each other in nearly the same parallel manner. There is no reason 



28 « Ueber den Begriff der Pflanzenart/ 1834, s. 14. 





