THE FOLIAGE 49 



consumed internally. The result is that in the daytime only 

 oxygen and no carbonic acid gas is given off. When it is dark, 

 carbon assimilation ceases, but not the process comparable 

 with breathing in animals. Thus oxygen is then absorbed 

 from the atmosphere and carbonic acid gas exhaled. There- 

 fore the old idea that plants were dangerous in a room at night, 

 though healthy in the daytime, like so many other old notions 

 based on observation, was correct from a scientific point of view. 



As every planter is aware, there is a season of the year when 

 growth is arrested and the trees winter, as it is called. Growth 

 in living creatures, plants included, is not a continuous increase ; 

 there are, necessarily, periods of rest and recuperation. It is 

 so with the Hevea, as with other trees. Before the time comes 

 for the period of recuperation and, therefore, for a temporary 

 cessation of the process of manufacture of the food-supplies 

 upon which growth is built up, all materials that may be of 

 further use to the tree gradually retire from the cells they 

 occupied in the leaves down the leaf-stalks to the twigs of the 

 trees. The leaves, in the cells of which remain only a lifeless 

 fluid, turn yellow and then brown or red. And thereafter the 

 time comes when the connection between the twigs and the 

 leaf-stalks is weakened by a growth of corky cells across the 

 base of the leaf-stalks, which thereby becomes brittle, and a 

 breath of wind brings the leaves fluttering to the ground. 

 With the corky cells the tree closes the doorway against fungi 

 on the watch. 



From the foregoing descriptions of the wonderful structure 

 of the Hevea it will be seen that while science explains much of 

 mystery in Nature, it never no, never affords or can afford 

 any rational explanation of the real mystery. What has been 

 aptly called " the solvent touch of science " may resolve for us 

 something of the construction of plants, something of the 

 materials employed in their wonderful structures and much of 

 interest in methods, but to accept these tentative interpreta- 

 tions and to say that that is all would be intellectual bank- 

 ruptcy. The greater the magnifying power of the microscope 

 the more of marvel becomes oppressively apparent. 



Life may sometimes appear as grey as a dull winter sky, 

 but a study of Nature brings out a radiant rainbow, stretching 

 from shore to shore and reaching to the very sky. 



