CHAP. I. 



ASPARAGUS. 



61 



the same general direction, but in a slightly zigzag manner, 

 until it became upright. On the following morning it changed 

 its course completely. There can therefore hardly be a doubt 

 that the plumule circumnutates, whilst buried beneath the 

 ground, as much as the pressure of the surrounding earth will 

 permit. The surface of the soil in the pot was now covered with 

 a thin layer of very fine argillaceous sand, which was kept damp; 

 and after the tapering seedlings had grown a few tenths of 

 an inch in height, each was found surrounded by a little open 

 space or circular crack ; and this could be accounted for only by 

 their having circumnutated and thus pushed away the sand on 

 all sides ; for there was no vestige of a crack in any other part. 

 In order to prove that there was circumnutation, the move- 

 Fig. 48. 



Asparagus officinalis : circumnutation of plumules with tips whitened and 

 marks placed beneath, traced on a horizontal glass. A, young plumule ; 

 movement traced from 8.30 A.M. Nov. 30th to 7.15 A.M. next morning ; 

 magnified about 35 times. B, older plumule ; movement traced from 

 10.15 A.M. to 8.10 P.M. Nov. 29th ; magnified 9 times, but here reduced 

 to one-half of original scale. 



ments of five seedlings, varying in height from '3 inch to 2 inches, 

 were traced. They were placed within a box and illuminated 

 from above; but in all five cases the longer axes of the figures 

 described were directed to nearly the same point ; so that more 

 light seemed to have come through the glass roof of the green- 

 house on one side than on any other. All five tracings re- 

 sembled each other to a certain extent, and it will suffice to give 

 two of them. In A (Fig. 48) the seedling was only 45 of an 



