C. E. FAWSITT. 



medicine, the number of conditions involved is so great 

 that we are never sure what all the conditions of the 

 experiment are. In the matter of the effect of a drug on 

 the human body, it is well known that personal idiosyn- 

 crasy is very marked. Not only will a dose of any drug 

 (less than the lethal dose) have very different effects, in 

 magnitude at least, on different people, but the same close 

 of a drug given to the same person at different times may 

 have different effects. In this case we all recognise that 

 the number of factors involved is so .great that it is im- 

 possible to know them all. 



Evolution of Matter. 

 I should like more particularly now to confine myself to 

 such points of interest as arise in a consideration of the 

 (terrestrial) evolution of matter, for even in that question 

 alone there is much both of uniformity and of irregularity 

 to arrest the attention. 



Atoms — Matter is Discontinuous in Structure. 

 For over 2000 years the question was debated as to 

 whether the structure of elements was continuous or dis- 

 continuous, i.e., whether atoms existed or not. The 

 existence of the atom was believed in at least as far back 

 as Democritus, 500 B.O. 



The atom, as the derivation of the word indicates, was 

 formerly always considered to be indivisible, and was at- 

 first considered as simply the smallest conceivable particle 

 of matter. 



After Dalton (1803-1808) had launched his Atomic 

 Theory, which is still accepted r the atom was defined as 

 the smallest particle of an element which could take part 

 in a chemical action. The atom has had to be believed in 

 without our being able to see it or any effect resulting 

 from its individual action, right down to this generation. 

 Now, at last, the traces of the action of single atoms can 



