musical and artistic temperament, responsive to every refined emotion, 

 hih quick perception and ready memory, his geniality and conversa- 

 tional powers, made his handsome presence everywhere acceptable.* 

 " Bonders was then," writes Moleschott with fervid admiration, " a 

 swelling rose-bud, whose calix leaves signified nothing but pure 

 science, the flower leaves hidden glory. In one word, he was a man 

 complete perfect for his time of life." His bright intelligence, 

 indeed, was able to assimilate without apparent effort all that it saw 

 and read of in the active world around a world then agitated by novel 

 questions, of absorbing interest, regarding the Constitution of the 

 Universe and the true import of Man's place and being in it. 



In those days very recent advances in the methods and aims of 

 exact research, as applied to various branches of science, had made it 

 possible to penetrate more deeply than ever before into many of the 

 profounder mysteries of nature, and some grand enlightenment 

 seemed near at hand. During the years following 1840, one concep- 

 tion in particular, that of the Conservation of Energy in Nature, long 

 foreshadowed, was rapidly assuming definite shape under the ordeal of 

 exact experiment pursued on many converging lines. It could hardly, 

 however, have been said to have become yet established, even in the 

 minds of the most advanced physicists, ere Bonders had clearly 

 recognised its far-reaching importance in its special application to 

 the Science of Life, the foundations of which his keen gaze was then 

 freshly exploring. In the winter of 1844, when but twenty-six, in 

 "only a lecture, not pretending," he modestly says, "to any high 

 scientific worth," he casts a glance on the change of matter as the 

 source of animal heat.f Here we already find him embracing in his 

 view all nature, and looking confidently to her most general and all- 

 pervading laws for the explanation of the enigma of life. " Animal 

 heat is chemical heat ;" but the final and irreversible proof of this, 

 he shows in detail, " can only be given when science shall have proved 

 that the quantity of heat in the animal body answers absolutely to 

 the chemical change which takes place there" "All working- in 

 nature, all life on earth, rests on the change of the elements from 

 which it is formed, but side by side with this change of matter 

 stands a change of forces. Both are inseparably bound up together. 

 As the change of matter is the condition without which no life exists, 

 so the change of forces is the condition without which no life gives 

 evidence of itself. An idea arises gradually in science, which finds 

 confirmation everywhere, absolute contradiction nowhere, an idea 



* His stature was 6 feet 1 inch ; circumference of bead, 24 inches, English. 



t " A Glance on the Change of Matter of Epitellurian Life as the Source of 

 Proper Heat of Plants and Animals," by Dr. Bonders, Military Doctor, 2nd Class, 

 at the Military School of Medicine, delivered in the Society of Sciences, Utrecht ; 

 Van der Post, Feb. 1845. [In Dutch, never translated.] 



