210 EVOLUTION, OLD AND NEW. 



syngenesia have been accustomed to contract together 

 in the evening, and thence if you stimulate any one of 

 them with a pin, according to the experiment of 

 M. CoIyoIo, they all contract from their acquired -asso- 

 ciations. 



" To evince that the collapsing of the sensitive plant 

 is not owing to any mechanical vibrations propagated 

 along the whole branch when a single leaf is struck 

 with the finger, a leaf of it was slit with sharp scissors, 

 with as little disturbance as possible, and some seconds 

 of time passed before the plant seemed sensible of the 

 injury, and then the whole branch collapsed a.s far as 

 tbe principal stem. This experiment was repeated 

 several times with the least possible impulse to the 

 plant. 



"V. 1. For the numerous circumstances in which 

 vegetable buds are analogous to animals, the reader is 

 referred to the additional notes at the end of *' Botanic 

 Garden,' Part I. It is there shown that the roots of 

 vegetables resemble the lacteal system of animals ; the 

 sap vessels in the early spring, before their leaves 

 expand, are analogous to the placental vessels of the 

 foetus ; that the leaves of Jand plants resemble lungs, 

 and those of aquatic plants the gills of fish ; that there 

 are other systems of vessels resembling the vena por- 

 tarum of quadrupeds, or the aorta of fish; that the 

 digestive power of vegetables is similar to that of 

 animals converting the fluids which they absorb- into 

 sugar ; * that their seeds resemble the eggs of animals, 



* ' On the Digestive Powers of Plants.' See Mr. Francis Darwin's 

 lecture, already referred to. 



