660 



SCIENTIFIC RECREATIONS. 



the plant material, which must originally have been derived by the action of 

 light. Light, therefore, is the great " producer." It gives life to plants 

 upon which animals feed, and therefore light is in one sense the beginning of 

 all things. We can now understand why light must have been created first. 

 Many interesting experiments can be made to observe the effect of 

 darkness and different coloured light (transmitted through coloured glasses) 

 upon plants ; and it will be observed that although the leaves may not 

 develop the natural green tint, the flowers will exhibit their usual colour. 

 One effect of light upon plants is to make them green. 



We all admire the beautiful green of the spring leaves, and the freshness 

 of the colours of the trees and grass. But if we pluck up a plant its root is 

 not green. Why then is the cleaned root not as green as the upper 



portion ? Because of the ab- 

 sence of light. There is a 

 substance called Chlorophyl 

 which, when acted upon by light, 

 becomes green. This is con- 

 tained in plants, and when the 

 daylight falls upon it the sub- 

 stance turns green. So, as we 

 said above, plants are not green 

 when kept in the dark. Celery 

 is a common instance. Heat, 

 of course, has much to do 

 with the activity or vitality of 

 plants, and the range extends 

 from just above freezing point 

 to 122 Fahr. We find tiny 

 plants blossoming in Alpine 

 regions close to the snow, and 

 others in full life in the tropics, 

 protected from the fierce rays 



Fig. 7 38.-Branchofelm. by scaly COV eringS and huge 



leaves. In the northern regions buds appear as soon as the surface warmth 

 is felt, and even when no heat can yet penetrate to the roots. Thus we see 

 that Nature fits the animal and the plant to the localities in which they 

 live, and they exist interdependently. Some can defy cold, others flourish 

 in drought ; some love moisture, others live in great heat encased in prickly 

 armour. 



With this introduction to biology we may now pass on to speak of the 

 seeds and germination of plants, which we divide into the flowering and non- 

 flowering species. We suppose that the appearance of various organs of 

 plants are familiar to our readers, and the root, the stem, the leaves, and 

 the flower itself, as well as the seeds, are well known, and their uses under- 

 stood, generally. 



