Growth and Movement. 119 



bean plant which has been grown in a pot, and kept 

 equally illuminated on all sides. Figure 5 1 shows the same 

 plant after revolving for eighteen hours on both horizontal 

 and vertical axes at the same time, so that both light and 

 gravity as a guide were useless to it. Its protoplasts ap- 

 pear to have perceived its abnormal condition, and have 

 changed the position of the leaves ; having no guide, how- 

 ever, only fruitless curvatures have resulted. 



Figure 52 represents the same plant after standing eigh- 

 teen hours in a normal position under equilateral illumina- 

 tion ; the protoplasts have found their direction again, and 

 have placed the leaves more nearly in their wonted position. 

 Figure 53 represents this plant after being next illuminated 

 on one side only for twenty-four hours ; the protoplasts of 

 both stem and leaves have attempted to bring the leaves 

 into position for receiving as much as possible of the inci- 

 dent light. Figure 54 shows the same plant again after 

 being equally illuminated on all sides for about twenty- 

 four hours ; since there was the same degree of light 

 intensity on all sides, gravity has evidently been em- 

 ployed to bring the parts back from their one-sided 

 position. 



Figure 55 is a photograph of another plant which has 

 grown in a pot under normal conditions. Figure 56 repre- 

 sents the same plant after standing inverted for about 

 eighteen hours while kept equally illuminated on all sides 

 by rotation on a vertical axis ; a very successful attempt 

 has been made to bring the leaves and stem back to their 

 normal relations to light and gravity. (To see this to best 

 advantage hold the book upside down.) Figure 57 shows 

 the same plant again after standing erect under equilateral 

 illumination, the stem and younger leaves having assumed 

 approximately their original positions. 



