Marvels of the Universe 



505 



Photo »y] 



[S. L. Baslin. 



LIGHT AND THE PLANT. 



The Rose of Sharon flower turns upward to the light in order that the flower 

 ly be properly displayed, but — 



way or another shun the Hght. 



We have seen that the i-\-y- 



leaves twist round in order to be 



fully illuminated ; but in the 



case of the young shoots of 



this plant there is a very marked 



tendency to avoid the light. 



Examine a plant of ivy which 



is gro\\-ing up a trunk or against 



a wall, and note how closely the 



growing shoots press against the 



support, stri\'ing their hardest 



to get away from the light. This 



avoidance of light is to be seen 



even more stronglj' in the case 



of the tendrils of the vine and 



the ampelopsis creeper. It is 



quite astonishing to watch the 



manner in which the delicate 



threads seem to search out the 



comers and cre\ices, just as if 



the}' had some definite knowledge 



of what they were doing. As 



a matter of fact, it is simply that they have been endowed with a tendency to grow away from 



the hght. This is, of course, a valuable habit, seeing that it is in the cracks of the wall that they 



are most likely to be able to find 



a suitable hold. i 



Although it does not entirely 

 explain the downward growth of 

 the root of the seedling, there 

 is small doubt that there exists a 

 tendency on the part of all under- 

 ground processes to get a\\ay from 

 the Ught. A pretty little experi- 

 ment, and one which is ver}' simple 

 to carry out, will prove this. Fill 

 a tumbler with water, and across 

 the top of this stretch a piece 

 of fine muslin. The material 

 may be readily fixed with a rubber 

 band or a portion of twine. On 

 the top sow a few seeds of white 

 mustard, and put the whole thing 

 under a glass shade. Place a 

 cloth covering over the shade so 

 that the seedlings will start life 

 in absolute darkness. After a 

 few days it will be seen that the 

 shoots have grown straight up 



•hk,- 



Photo iw] 



— when the seed vessel is almost ripe the 

 light until the capsule bends towards th 

 ripened seeds. 



LIGHT AND THE PLANT. 



tern gradually turns away from the 



arth that shall 



receive the 



