G YRA TION OF PLANTS. 159 



growing points at a slow rate, and over a small space 

 during six successive days. 



The stems of some plants only describe one large 

 ellipse during twenty-four hours, others describe 

 several smaller ones.' A plant which describes but 

 one ellipse during one day, may on the next describe 

 two smaller ones. Sometimes the course is almost 

 circular, but generally elliptical, and the ellipse may 

 be broad or very narrow. Whatever the figure may 

 be it is not a regular one, but varied by loops or 

 zigzag vibrations in other directions. 



In coniferous trees it was observed by Dr. 

 Masters in 1878 1 that the leading shoot has a 

 rotatory movement, and this has subsequently been 

 confirmed by him, in Abies Nordmanniana. The 

 same authority has also directed attention to other 

 movements which affect the leaves, and relate to 

 modified forms of heliotropism. " Some of the 

 silver firs," he says, " are endowed with a power of 

 motion by means of which the leaves are raised or 

 lowered. M. Chatin asserts that in the middle of 

 the day the plant (Abies Nordmanniana) has a pre- 

 dominant green hue, but when the light is more 

 diffused, as in the evening or early morning, then 

 the plant assumes a milky-white appearance. This 

 appearance is due to the elevation of the glaucous 



1 " Gardener's Chronicle," 1878, pp. 247 and 826. 



