50 ANNITEESAEY ADDRESS 



''"When, one step broken, the whole scale's destroyed; 

 From Nature's chain, whatever link you strike. 

 Tenth, or tea thousandth, breaks the chain alike:" 



It may be useful sometimes to take a general view of the 

 universe, and to endeavour to trace where the different natural 

 sciences interlace with each other, and to find out what general 

 laws animate and govern the whole. A student of medicine is more 

 fitted to take this general view of nature than many people, be- 

 cause he must know a little of so many sciences. His motto should 

 be, '■'■Homo sum; humani nihil a me alienum puto,^'' — "I am a 

 man; I sympathise with everything human," for all the sciences 

 have their focus in man. 



The thoughts that I wish to bring before your notice this evening 

 may be classed iinder the title of " A Sketch of the Plan of Nature." 

 Theories of the plan of Nature have always been numerous. 

 Groundless hypotheses regarding the origin of living beings existed 

 in profusion some two centuries ago. Drelincourt took the trouble 

 to enumerate no less than 262 ; and Blumenbach quaintly remarks 

 that doubtless his theory formed the 263rd. 



During the last few years discoveries have been made and 

 theories have been advanced, which, if followed to their legitimate 

 conclusions, must greatly modify our views regarding the plan and 

 the laws of nature. I allude to the theories which are included 

 under the term Darwinism, the laws of the correlation of forces, 

 the conservation of energy, etc., and to the discovery of that 

 wonderful and suggestive little instrument, the radiometer. 



The Nebular Theory of Laplace is the one which is most 

 generally accepted as accounting for the present state of the 

 universe. It supposes that the solar system, and others, once 

 existed in a state of intense heat, in a nebulous condition or as 

 matter finely divided, and that this diffuse mass of matter, gradually 

 cooling, condensed towards its centre and thus formed the sun, 

 while the planets were formed by the condensation of external 

 rings. There are several objections to this theory. If the planets 

 were formed from the same nebulous matter as the sun, they 

 should resemble him in chemical constitution. Now the sun has 

 elements in him, as revealed by spectrum analysis, which are not 

 known to exist in the earth, and some elements exist in the 

 earth which have not been found in the sun. And again we have 

 no historical proof that the sun is gradually cooling, and the evi- 

 dence of Geology is against the supposition ; for we do not find 

 that the climate of the earth has gradually got colder, but we have 

 distinct proof of an alternate hot and cold climate. If the sun is 



