Appendix. 177 



We have nothing to do just now with the question how these 

 bodies came there and what they are for, though it suggests a 

 very interesting line of investigation. The position of the chlo- 

 rophyll bodies in the cell, and their movements under the influ- 

 ence of varying intensities of light, are all that will here be 

 considered. 



If the plant has been kept on a short allowance of light, the 

 chlorophyll bodies will be found arranged in planes parallel to 

 the leaf surface, as if they would expose themselves as fully as 

 possible to the little light which falls upon them ; but if the plant 

 has been in bright sunlight, they will be found in line along the 

 side-walls of each cell, as if to hide themselves in a measure from 

 the intense light. And further, if the plant which has been in 

 darkness or in diffused light, and in whose cells the chlorophyll 

 bodies are arranged in the former position, is now placed in 

 direct sunlight, it will take but a short time for them to assume 

 the latter position, and vice versa. 



r rhis curious fact has been known only a few years, but 

 within that time it has been repeatedly observed by the best 

 European botanists, and is now as well established as any other 

 phenomenon of vegetable life. 



With a view to confirming this fact by actual observation, a 

 detailed experiment was performed, March 4th, 1876. A bunch 

 of moss had been kept in a room for several days. No special 

 pains were taken with it, except that it was kept moist and for 

 two days had been turned bottom upwards so as to cut off the 

 light more effectually. It was in good, healthy condition, with 

 soil around the roots which had been taken up with it when it 

 was brought from the woods. It had not, then, been exposed to 

 direct sunlight for several days, and if any light reached it at all, 

 it must have been very faint. 



Just before noon, six fresh leaves were examined, from differ- 

 ent stems of the bunch. In this and in the subsequent examina- 

 tions, pains were taken to select delicate young leaves, it being 

 supposed that they would be most susceptible to the influence to 

 be tested. The result was as follows: In five out of the six 



