Chap. XXVI. COMPENSATION. 335 



probably depends on multiple parts being of less physiological 

 importance than single parts ; consequently their structure 

 has been less rigorously guarded by natural selection. 



Compensation of Growth, or Balancement. — This law, as 

 applied to natural species, was propounded by Goethe and 

 Geoffroy Saint-Hilaire at nearly the same time. It implies 

 that, when much organised matter is used in building up 

 some one part, other parts are starved and become reduced. 

 Several authors, especially botanists, believe in this law ; 

 others reject it. As far as I can judge, it occasionally holds 

 good ; but its importance has probably been exaggerated. It 

 is scarcely possible to distinguish between the supposed 

 effects of such compensation, and the effects of long-continued 

 selection which may lead to the augmentation of one part, 

 and simultaneously to the diminution of another. Anyhow, 

 there can be no doubt that an organ may be greatly increased 

 without any corresponding diminution of an adjoining part. 

 To recur to our former illustration of the Irish elk, it may be 

 asked what part has suffered in consequence of the immense 

 development of the horns ? 



It has already been observed that the struggle for existence 

 does not bear hard on our domesticated productions, and con- 

 sequently the principle of economy of growth will seldom 

 come into play, so that we ought not to expect to find with 

 them frequent evidence of compensation. We have, however, 

 some such cases. Moquin-Tandon describes a monstrous bean, 7 

 in which the stipules were enormously developed, and the 

 leaflets apparently in consequence completely aborted ; this 

 case is interesting, as it represents the natural condition of 

 Lathyrus aphaca, with its stipules of great size, and its leaves 

 reduced to mere threads, which act as tendrils. De Can- 

 dolle 8 has remarked that the varieties of Baphanus sativus 

 which have small roots yield numerous seed containing much 

 oil, whilst those with large roots are not productive in oil ; 

 and so it is with Brassica asperifolia. The varieties of 



7 ' Tcratologie Veg.,' p. 156. See 1875, p. 202. 

 also my book on ' The Movements and 8 'Memoires du Museum,' &c, 



Hubits of Climbing Plants,' 2nd edit, torn. viii. p. 178. 



