THE FORMS OF FLORAL ORGANS. 113 



Now, it might be argued, that when one organ changes 

 its form others must do so in obedience to the " laws of cor- 

 relation of growth," as IMr. Darwin showed to be the case 

 with the feet and bills of pigeons. In plants, however, the 

 connection between various parts, even in close proximity, is 

 by no means so intimate as between different organs of the 

 higher animals ; while the theory advanced here gives a 

 common interpretation for the whole of the so-called correla- 

 tions found in any flower. That one is justified in saying 

 that correlated growths are much restricted in plants, is 

 clear from the experience of horticulturists ; thus, while, 

 e.g., the varieties of pease are infinite, they having been the 

 object of selection alone, the flowers which produce them 

 have virtually remained unchanged. 



A single coincidence has little or no scientific weight as 

 indicating cause and effect. It is only when coincidences 

 can be multiplied that they furnish a probability of a high 

 order ; which, even if they do not admit of a verifiable ex- 

 periment, still furnish a moral conviction, which, by the rules 

 of philosophy, is equivalent to a demonstration. Now, this 

 is exactly the case with irregular flowers. They always 

 occur in similar positions ; they are always constracted so 

 that the insect in adaptation to them can gain access to 

 the honey in the easiest way ; their organs are so situated 

 that the pollen should be transferred accurately to the 

 stigma, etc. And when we find them distributed every- 

 where throughout phanerogamous plants, the probability 

 that the same or analogous causes have brought them about 

 is of a very high order indeed 



Moreover, since we have abundant evidence of the re- 

 sponsive power of protoplasm to build up tissues wherever 

 they are required, I am not assuming an influence on the 

 one hand without ample evidence of the probability of the 



