74 THE BIOLOGY OF DAILY LIFE. 



decimal proportion, as the vertical columns in common 

 arithmetic ; then our expression (B) + (C) = 22, but 

 if you are mentally calcareous, and a good controver- 

 sialist, and fond of sparring without altering a single 

 fact of the external world or figure on your paper, you 

 may behold your first column thus : jc! ; or, instead of 22, 

 you see | which make four, and expatiate eloquently 

 on the unscientific, unphilosophical, theological, meta- 

 physical, or what not, minds who cannot see that 

 two and two make four. 



Now the reader will know what I mean by the calc- 

 spar, or double refraction fallacy, and we return 

 joyfully to the " Lay Sermon." 



" The statement that a crystal of calc-spar 

 consists of carbonate of lime is quite true, if we 

 only mean that by appropriate processes, it 

 may be resolved into carbonic acid and quick- 

 lime. If you pass the same carbonic acid over 

 the very quicklime thus obtained, you will 

 obtain carbonate of lime again ; but it will not 

 be calc-spar, nor anything like it. Can it, 

 therefore., be said that chemical analysis teaches 

 nothing about the chemical composition of calc- 

 spar? Such a statement would be absurd; 

 but it is hardly more so than the talk one 

 occasionally hears about the uselessness of 

 applying the results of chemical analysis to the 

 living bodies which have yielded them." 

 Every chemist and biologist must agree to all this. 

 We know there is at least the beginning of a science 

 of animal chemistry which has already given us results 

 of nearly priceless value. But let us carefully note 

 Professor Huxley's method of dealing with the results 



