HORTICULTURAL SOCIETY OF LONDON. 



347 



was quite dry, that in the latter retained the moisture. This ex- 

 l)eiiment was repeated several times with similar results, and I 

 was, therefore, led to believe that the moisture in the soil was the 

 chief cause of the seeds germinating sooner under the blue 

 glass, and that the chemical effects of the coloured rays was 

 imaginary. 



To prove whether or not this opinion was correct, seeds of the 

 same plant were sown andcovercd with two common hand-glasses; 

 the patches were both watered alike, and one of the glasses was 

 shaded with a mat. The same results were obtained in this case 

 as in the former ; that is, the seeds vegetated soonest under the 

 shaded glass, but as the plants grew they became drawn and 

 weakly, resembling those under the blue glass. 



In order to carry out the experiment, and render it as complete 

 as possible, a small box or frame was made and divided into 

 eight parts, the first of which was glazed with common glass, and 

 the others with the seven prismatic colours — red, orange, yellow, 

 green, blue, indigo and violet. The seeds of Nemophila were 

 sown in each, the whole were watered alike, and the frame 

 was put on. On the fourth day after this was done, the seeds 

 under the red, green, indigo and violet glasses were above 

 ground; those under the blue came up next, then those under 

 the orange and yellow, and last of all under the common glass. 

 The experiment was repeated again and again with diiferent 

 kinds of seeds in the course of last summer, with the same 

 result, providing the weather was bright and fine. It will be 

 seen, therefore, that the same thing happened in this experiment 

 as in the other ; namely, that the seeds vegetated soonest where 

 there was least evaporation going on, and vice versa. But the 

 shade under the darker glasses was too much for the young 

 plants, they very soon became drawn and weakly, and formed 

 a striking contrast to those under the common hand-glass. 



In the autumn, or when the sky was cloudy for a few days, 

 during some of the experiments, the seeds under the orange 

 and yellow glass vegetated sooner than those under any of the 

 others, 'i his is very easily explained — the orange and yellow 

 glasses aflbrded sufficient shade during weather of this kind, and 

 at the same time admitted more heat to the soil than the darker 

 ones, and consequently the results (when these things are con- 

 sidered) are such as might have been expected. 



Many experiments with cuttings were also tried with the same 

 frame, and if the sky chanced to be clear for some days after the 

 cuttings were planted, they did much better under the dark 

 glasses, but when dull weather came they generally suffered 

 much from damp, and in no instance did they succeed so well 

 as under a common shaded frame. After watching these experi- 



