238 Anniversary Address. 



gists. We can only judge of atoms and molecules by the re- 

 sult of chemical combinations, or by their effect as atmos- 

 pheric components. They are invisible, and no microscope 

 is likely to reveal their form to the eye. In the list of 

 elementary bodies an atom of Hydrogen is taken as No. 1 

 or the lightest, and gold is one of the heaviest being 196 

 times the weight of Hydrogen. Thorium which is 233'9 times 

 heavier than Hydrogen is the most dense. These atoms in 

 various combinations enter into nature organic and inor- 

 ganic ; the most simple and the most complex structure 

 differing only in the manner and proportion in which these 

 elements are combined and arra^nged. 



Can inorganic combinations, then, of themselves work out 

 the problem of a living organism ? Can a fermenting vege- 

 table organism produce animal life ? These are questions 

 which the great Des Cartes in the first case and Professor 

 Tyndall in the latter think they have satisfactorily solved. 



Des Cartas had a bias towards deductive reasoning — his 

 contemporary Bacon to induction. 



"Des Cartes was the first to reduce, in a manner eminently 

 capable of bearing the test of mental presentation, vital 

 phenomena to purely mechanical principles. Through fear or 

 love Des Cartes was a good churchman ; he accordingly rejected 

 the notions of an atom, because it was absurd to suppose that 

 the Creator if he so pleased, could not divide an atom ; he puts in 

 the place of the atoms small round splinters and light particles 

 out of which he builds the organism. He sketches with marvel- 

 lous physical insight a machine, with water for its motive power, 

 which shall illustrate vital actions. He has made clear to his 

 mind that such a machine would be competent to carry on the 

 processes of digestion, nutrition, growth, and respiration, and the 

 beating of the heart. Had Des Cartes been acquainted with the 

 steam engine, he would have taken it, instead of a fall of water, 

 as his motive power, and shown the perfect analogy which exists 

 between the oxidation of the food in the body and the coal in 

 the furnace."^'" 



It is difficult to conceive how an able thinker such as Des 



* Prof. Tyndall's Address to British Association. 



