TI1E BIOLOGY OF DAILY LIFE. 



"Apparent rari nantes in yurgite vasto." But the 

 inexorable logic of fact and natural law disposes even 

 of these hardy and vigorous few that can keep above 

 water when the four conditions are enforced. 



This fifth condition is, 



That the signs and symptoms of the particular 

 disease should be definite, and such main symptoms so 

 constant that the diagnosis should always be perfectly 

 reliable; nay, it is demanded for perfect proof that the 

 disease should be in itself a sort of definite entity, 

 recognizable and definable, otherwise than by its 

 (supposed) connection with the microbe. 



The whole reasoning is simply an illustration of the 

 fallacy called " arguing in a circle," for the limit which 

 defines what symptoms shall or shall not be regarded 

 as diagnostic of the particular disease is this very con- 

 nection with the microbe, which has to be proved 

 pathogenetic. 



It would force me to bring in medical details, 

 unsuited to this little work, if I were to furnish proofs 

 of this latter statement here, but any student can verify 

 for himself the truth of my remark, and even the 

 "general reader," if he has ever glanced at medical 

 literature, must be aware that the fifth condition never 

 has and never can be complied with. 



We next turn to the micro-organisms themselves. 

 How are they identified ? We know what a difficult 

 matter is this question of identity (I do not refer to meta- 

 physical difficulties connected with personal identity), 

 but physical identity is a difficult and perplexed 

 subject. We have known the greatest experts have 

 sometimes been deceived, and cases of mistaken 

 identity are not un frequent. It is true in the case of 



