416 THE CANADIAN NATURALIST. [DeC. 



are known to breed far north, althougli the migration of species 

 will be found one of the most interesting studies in the economy of 

 animal life. 



THE CORRELATION OF VITAL AND PHYSICAL 



FORCES.^i^ 



By Prof. Geo. F. Barker, M.D., of Yale Colioge. 



In the Syracusan Poecile, says Alexander von Humboldt in his 

 beautiful little allegory of the Rhodian Genius, hung a painting, 

 which, for full a century, had continued to attract the attention 

 of every visitor. In the foreground of this picture a numerous 

 company of youths and maidens of earthly and sensuous appearance 

 gazed fixedly upon a haloed Genius who hovered in their midst. A 

 butterfly rested upon his shoulder, and he held in his hand a 

 flaming torch. His every lineament bespoke a celestial origin. 

 The attempts to solve the enigma of this painting — whose origin 

 even was unknown — though numerous, were all in vain, when one 

 day a ship arriving from Rhodes, laden with works of art, brought 

 another picture, at once recognized as its companion. As before, 

 the Genius stood in the center, but the butterfly had disappeared, 

 and the torch was reversed and extinguished. The youths and 

 maidens were no longer sad and submissive, their mutual embraces 

 announcing their entire emancipation from restraint. Still unable 

 to solve the riddle, Dionysius sent the picture to the Pythagorean 

 sage, Epicharmus. After gazing upon them long and earnestly, 

 he said : Sixty years long have I pondered on the internal springs 

 of nature, and on the difierences inherent in matter; but it is only 

 this day that the Pvhodian Genius has taught me to see clearly 

 that which before I had only conjectured. In inanimate nature; 

 everything seeks its like. Everything, as soon as formed, hastens 

 to enter into new combinations, and nought save the disjoining art 

 of man can present in a separate state ingredients which ye would 

 vainly seek in the interior of the earth or in the moving oceans of 

 air and water. Different, however, is the blending of the same 

 substances in animal and vegetable bodies. Here vital force 

 imperatively asserts its rights, and heedless of the afiinity and 

 antagonism of the atoms, unites substances which in inanimate 



* Lecture delivered before the American Institute, Xew York in 1870. 



