No. XXXIV.] APPENDIX. 367 



frames; others require it more subdued, — for instance, tte ferns which 

 grow in the caves. Then again, we are obliged to shield some of our plants 

 from the Hght, such as the orchids ; and lastly, we have to grow some in 

 dark caves, as in the case of some fungi, and other of the lower plants 

 •which require almost a total exclusion of light. Now with regard to Kght, 

 we place our plants which require little light on a North aspect, and those 

 which require much light on a South aspect, but we must also shade our 

 houses. One of the best plans for shading is to make use of coloured 

 glass, which filters out many of the rays. This plan is adopted in the 

 Royal Gardens at Kew, where it seems to answer very well. At Paris they 

 have series of pantUe laths placed side by side, leaving a little gap between 

 them ; and lastly we cut off the light from many of our plants by putting 

 a linen shade over oiu" houses. Now, unless you regulate the light, you 

 may give up all idea of cultivation. It is no use to try without it, for you 

 cannot succeed. 



Well then, besides Hght, every plant requires a certain amount of 

 heat, and unless it has this it will not grow. It will be in vain for you to 

 try to grow the sugar-cane in this climate ; it would be in vain for you to 

 try to grow the geranium in Jamaica : for the sugar-cane would not 

 have enough heat here, and the geranium would have too much heat in 

 Jamaica, so that in either case the plant would be destroyed. Tou must 

 know, then, the right temperature at which the plant will grow. If you 

 employ more heat than what is required, as is usual in this country, your 

 plant will die. When I was at Florence, a botanist told me that he could not 

 grow Alpine plants there, the climate was too hot. With regard to heat a 

 very curious thing must be noticed, and that is, that heat must be applied 

 at certain intervals. Heat and light must be applied to every plant, so 

 that the plant rests and then grows, and then rests again. Rest is as 

 necessary to a plant as it is to man, and many of our plants are not able 

 to be succesrfuUy grown because we are not able to give them their precise 

 intervals of rest and growth as in their native spots. The Alpine plants 

 in the summer are exposed to the full heat of the sun, but in winter they 

 are kept warm by a thick covering of snow. 



Now, not oiily do we have these considerations of light and heat, but a 

 certain condition of the atmosphere is absolutely necessary to vegetation ; 

 there must be a certain amount of moisture in the air. It must be dry at 

 the right time, it must be wet at the right time; and unless you are 

 acquainted with the proper time to apply moisture and to withhold it, your 

 garden will be a failure. Take the delicate vine : it sprouts in spring and 

 requires the air to be moist. If you expose it to a dry atmosphere, you 

 injure the tissues of the plant ; but if you carry on your moisture above a 

 certain point, the plant will keep on growing and be injured. During the 

 period when the leaves are sprouting a damp atmosphere is necessary ; as 

 it forms its berries the atmosphere is gradually dried, and when the fruit 

 attains perfection you give all the air and light you can, and a much drier 

 atmosphere than you had before. 



Now we all know that electricity is an important agent in nature. 

 Some years ago some extraordinary ideas were put forward as to the effects 

 of electricity upon plants. So far as we know, at the present moment, all 

 we can say is, that we know not at all what effect electrical force has upon 

 plants, either upon their growth or maturation. Experiments were tried 



