THE LAW OF CONCORD IN NATURE 27 



of the community of strenuous organisms. I have found the 

 analogy with sex everywhere helpful to illustrate that there is 

 a norm of healthy and legitimate feeding. The study of sex has 

 shown that certain modes of protoplasmic union, though quite 

 possible for a time, are yet abnormal and, in so far as they would 

 lead to stagnancy, are really " abhorred " by progressive Nature. 



For some 150 years it has become apparent that flowers are 

 adapted to be crossed. Darwin's famous aphorism that " Nature 

 abhors perpetual self -fertilisation," sums up the results of his 

 classical experiments on the subject, although it still leaves us 

 in the dark as regards the real cause of this " abhorrence." It 

 is, however, remarkable that Darwin again and again felt driven 

 in some cases to distinguish between " legitimate " and " illegiti- 

 mate " fertilisations merely in view, of course, of results. It 

 is also significant that the immediate results in Darwin's experi- 

 ments frequently seemed to show that self-fertilisation was not 

 prejudicial to size and numbers. It was only after a great 

 number of generations that what I would consider to be a true 

 super-adequacy of force, due to legitimate and progressive, 

 i.e., genuinely co-operative union, such as obtainable with cross- 

 breeding, became apparent. It was the remoter and permanent 

 result, be it remembered, that led Darwin to his classical pro- 

 nouncement as to the superiority of cross- over self -fertilisation. 

 The subject is of so great an importance that it will be as well 

 to let Darwin himself speak on its history : 



There is weighty and abundant evidence (he says in The Effects of Cross 

 and Self-Fertilisation) that the flowers of most kinds of plants are con- 

 structed so as to be occasionally or habitually cross -fertilised by pollen 

 from another flower, produced either by the same plant, or generally, as 

 we shall hereafter see reason to believe, by a distinct plant. . . . Long 

 before I had attended to the fertilisation of flowers, a remarkable book 

 appeared in 1793 in Germany: Das Entdeckte Geheimniss der Natur, by 

 C. K. Sprengel, in which he clearly proved by innumerable observations, 

 how essential a part insects play in the fertilisation of many plants. But 

 he was in advance of his age, and his discoveries were for a long time 

 neglected. 



In the introduction of his book (p. 4) Sprengel says, as the 

 sexes are separated in so many flowers, and so many other 

 flowers are dichogamous, " it appears that Nature has not willed 

 that any one flower should be fertilised by its own pollen." 



In 1862 (says Darwin), I summed up my observations on Orchids by 

 saying that nature " abhors perpetual self -fertilisation." If the word 

 perpetual had been omitted, the aphorism would have been false. 



