88 



UPWARD GROWTH OF THE HEAD, AXD pt. ii. 



with a cliimney-pot 2 feet 7 inches high, and filled it 

 with earth, leaving only the five plants whose heads 

 had come out below. I placed the experiment out of 

 doors, supported from below. The five plants grew in 

 1845. In the spring of 1846 I cut off all except one 

 plant, and placed a second chimney-pot above the first 

 one. 



In March 1850 I placed a third chimney-pot on 

 the second, making the column of earth 7 feet 5 inches 

 in height. The roots had already reached the top of 

 the second chimney-pot, about 5 feet in vertical . 

 height ; and in June 1850 the plant itself was 7 feet 

 8 inches high. In the autumn of 1851 the roots were 

 near the top of the third chimney-pot, having grown 

 vertically upward about 7 feet. The plant itself was 

 within an inch of 9 feet. In the spring of 1852 I 

 raised the column of earth to 8 feet 1 inch, and in the 

 summer the plant was 9 feet 8 inches high. 

 Upward In otlicr similar experiments the soft gemmules, or 



growth of 



first gem- stcms, of s^ardcu beans and scarlet-runners forced 



mule when ^ 



ofiMit"^ themselves upward through about 10.^ inches of earth, 

 came through the holes of the flower-pot, and grew 

 towards the light till the runners required training. 



Hence it would appear that, while in the earth, the 

 first gemmules have a straight upward tendency inde- 

 pendent of light. If we attribute the straightness to 

 turgescence, I do not see why the growth should be in 

 a straight line up more than down^ or in any other 

 direction. But the gemmule seems beautifully en- 



