CH. nr. DOWNWARD GROWTH OF THE ROOTS. 95 



imagine that there must be something perfectly distinct 

 in the nature or cehular organisation of the original 

 first or tap-root of seedlings, as compared with that of 

 their branch-roots : though I cannot guess by what 

 agent the growth of the differing structure of the tap 

 and branch-root is to be directed in their differing 

 course, any more than I can guess the agent which 

 determines the upward growth of the first gemmule of 

 a seedling while it is in the earth, and before it reaches 

 the hght. 



Still farther to test this idea, which these experi- 

 ments gave me, — that first or tap roots alone would 

 appear below, and that no branch-roots would do so, — 

 in March, 1846, I placed cuttings of gooseberry and 

 currant in a pot of earth inverted on wire, and sus- 

 pended in the air. The cuttings struck, and no roots 

 appeared below ; the cause being, as I conceive, that, 

 as there were no seedhng-roots, so there were no tap- 

 roots. In July I destroyed all the cuttings except one 

 currant, placed the experiment on a support from below 

 and removed the flower-pot. There were a great 

 many roots growing in all directions round and over 

 the outside of the ball of earth. I replaced the flower- 

 pot with a large chimney-pot, which I filled with earth. 

 In 1847 the main shoot of the curi'ant slip was 4 feet 

 1 inch in height. In March, 1848, I placed a second 

 chimney-pot on the first ; and the plant grows and bears 

 fruit now, 1853. 



From the results of these experiments, I think it 



