1844— 1858] LAW OF BALANCEMENT 57 



[Sep. 1846]. Letter 23 

 Have you ever thought of G. St. Hilaire's " loi de 

 balancement," 1 as applied to plants ? I am well aware that 

 some zoologists quite reject it, but it certainly appears to me 

 that it often holds good with animals. You are no doubt 

 aware of the kind of facts I refer to, such as great develop- 

 ment of canines in the carnivora apparently causing a 

 diminution — a compensation or balancement — in the small 

 size of premolars, etc. I have incidentally noticed some 

 analogous remarks on plants, but have never seen it discussed 

 by botanists. Can you think of cases in any one species in 

 genus, or genus in family, with certain parts extra developed, 

 and some adjoining parts reduced? In varieties of the same 

 species double flowers and large fruits seem something of 

 this — want of pollen and of seeds balancing with the in- 

 creased number of petals and development of fruit. I hope 

 we shall see you here this autumn. 



In this year (1847) Darwin wrote a short review of Waterhouse's 

 Natural History of the Mammalia, of which the first volume had appeared. 

 It was published in The Annals and Magazine of Natural History, 

 Vol. XIX., p. 53. The following sentence is the only one which shows 

 even a trace of evolution: "whether we view classification as a mere 

 contrivance to convey much information in a single word, or as something 

 more than a memoria technica, and as connected with the laws of creation, 

 we cannot doubt that where such important differences in the generative 

 and cerebral systems, as distinguish the Marsupiata from the Placentata, 

 run through two series of animals, they ought to be arranged under heads 

 of equal value." 



A characteristic remark occurs in reference to Geographical Distri- 

 bution, " that noble subject of which we as yet but dimly see the full 

 bearing." 



The following letter seems to be of sufficient interest to be published 

 in spite of the obscurities caused by the want of date. It seems to have 

 been written after 1847, m which year a dispute involving Dr. King and 



1 According to Darwin (Variation of Animals and Plants, 2nd ed., 

 II-, p. 335) the law of balancement was propounded by Goethe and 

 Geoffroy Saint-Hilaire (1772 — 1S44) nearly at the same time, but he 

 gives no reference to the works of these authors. It appears, however, 

 from his son Isidore's Vie, Travau.x &*c, d'E/ienne Geoffroy Saint- 

 Hilaire, Paris 1847, P- 2I 4> that the law was given in his Philosophie 

 Analomioue, of which the first part was published in 181 8. Darwin 

 {ibid.) gives some instances of the law holding good in plants. 



