386 FRAGMENTS OF SCIENCE. 



journals I find recorded ponderings and speculations 

 relating to these subjects, and attempts made, by refer- 

 ence to magnetic and crystalline phenomena, to present 

 some satisfactory, image to the mind of the way in 

 which plants and animals are built up. Perhaps I 

 may be excused for noting a sample of these early 

 speculations, already possibly known to a few of my 

 readers, but which here finds a more suitable place than 

 that which it formerly occupied. 



Sitting, in the summer of 1855, with my friend Dr. 

 Debus under the shadow of a massive elm on the bank 

 of a river in Normandy, the current of our thoughts and 

 conversation was substantially this : We regarded the 

 tree above us. In opposition to gravity its molecules 

 had ascended, diverged into branches, and budded into 

 innumerable leaves. What caused them to do so 

 a power external to themselves, or an inherent force ? 

 Science rejects the outside builder ; let us, therefore, 

 consider from the other point of view the experience 

 of the present year. A low temperature had kept 

 back for ^yeeks the life of the vegetable world. But 

 at length the sun gained power or, rather, the cloud- 

 screen which our atmosphere had drawn between him 

 and us was removed and life immediately kindled 

 under his warmth. But what is life, and how can 

 solar light and heat thus affect it? Near our elm 

 was a silver birch, with its leaves rapidly quivering in 

 the morning air. We had here motion, but not the 

 motion of life. Each leaf moved as a mass under the 

 influence of an outside force, while the motion of life 

 was inherent and molecular. How are we to figure 

 this molecular motion the forces which it implies, 

 and the results which flow from them ? Suppose 

 the leaves to be shaken from the tree and enabled 



