APPENDIX 355 



or rather upon a chlorophyll granule. The ray was extin- 

 guished when it struck the granule ; it ceased to be light any 

 longer, but it did not cease to exist. It was used up in the work 

 it did inside the granule : it broke the connexion between the 

 atoms of carbon and oxygen which were combined as carbonic 

 acid. The Uberated carbon in some way or other combined 

 with water and formed starch. This starch was transformed 

 into sugar, and after many peregrinations inside the plant was 

 pfecipitated again inside the grain as starch, or as gluten. In 

 either case it entered into the composition of bread, which 

 serves us as food. It was transformed into our muscles, into 

 our nerves. And now in our organisms atoms of carbon strive 

 to recombine with the oxygen which is carried by the blood to 

 all the parts of our body. The ray of sunUght, concealed in 

 these atoms during this process in the form of chemical tension, 

 reacquires the form of actual energy. It is this ray of sunlight 

 which warms us, and by which we move. May be it sparkles 

 in our brains at the present moment. 



This illustration is the most detailed answer which science 

 can give in reply to our question. We can express it shortly 

 in three words. Food plays in our organism the part of a 

 source of energy only because it is a preserve of sunshine. 



The scientific importance of this result is obvious. It 

 will also be appreciated by people indifferent to scientific 

 truths. A poetical dreamer who looks sadly upon the prosaic 

 labour of a scientist wiU be pleased to learn from him that he — 

 the poet himself— is much the same ethereal being, built of air 

 and Ught, as the immaterial productions of his fancy. The 

 haughty noble who prides himself upon his ancestry, and looks 

 down somewhat contemptuously upon the modest lot of the 

 toilers on the field of science, wiU certainly treat with more 

 respect this same science on hearing that she entitles him as well 

 as the Emperor of China to call himself ' the Son of the Sun.' ^ 



' Helmholtz: Ueber die Wechselwirkung derNaiurhmfte,'p. 127. 



