240 FIRESIDE SCIENCE, 



movements. Wherever the rays of sunlight fall, 

 there is never perfect rest ; and this relates to the 

 vegetable as well as to the animal world. Sunlight 

 is pregnant with life; no matter how slant may be 

 the rays, or how few the hours during the twenty- 

 four they may fall upon the earth. In winter the 

 really useful plants cannot grow, but in the lower 

 forms of cryptogamic plants the processes of vege- 

 tation are quite active. The mosses, lichens, liver- 

 worts, etc., resist cold wonderfully, and they will 

 grow at very low temperatures. We find them 

 under snow-banks and sheets of ice in winter keep- 

 ing up an active circulation, so active that they are 

 able to ripen their sporangia or mature their fruit, 

 with the thermometer close upon zero. Lichens 

 are so constituted as to be able to reverse the order 

 of nature, and take their winter nap in summer. 

 In the cold months their vegetating period occurs, 

 and they are then most active. The lichens are 

 a very low order of plants ; but we must not look 

 upon them with contempt, for from their existence, 

 or by their creation, life upon our planet is ren- 

 dered possible. The poor, humble lichens came 

 before man ; and man would never have come at 

 all, if the lichens had not preceded him. These 

 plants are the very first which made their appear- 

 ance upon the rocks, when our earth was barren 

 and chaotic ; and dying there, they prepared the 



