452 SCIENTIFIC THOUGHT. 



i.e., the generation of living out of dead or not-living 

 matter. 



But in proportion as abiogenesis or spontaneous 

 generation has disappeared from our scientific text- 

 books, life being recognised as a phenomenon between 

 which and dead matter there exists no intelligible 

 and no practical transition except that of destruction, 

 so. the ubiquity of life has forced itself more and more 



The ubiquity 



of life. on our attention. Not long ago, as Huxley tells us, 

 the adherents of spontaneous generation urged as an 

 argument on their side that if biogenesis be true, 

 innumerable facts and experiments prove " that the air 

 must be thick with germs ; and they regarded this as 

 the height of absurdity. But nature," as Huxley con- 

 tinues, " occasionally is exceedingly unreasonable, and 

 Professor Tyndall has proved that ordinary air is no 

 better than a sort of stirabout of excessively minute 

 solid particles." It is now, after a generation has passed, 

 hardly necessary ta refer to any special experiments of 

 Tyndall or of others, when the daily press brings us 

 records of the number of billions of germs contained in 

 a cubic inch of the atmosphere of large cities, precisely 

 as it does of the mortality of their population. The 

 cellular theory of disease has been succeeded and ampli- 

 fied by the bacillar theory, and no modern scientific fact 

 has fastened on the popular mind with a stronger hold 

 than the ubiquity of the micro-organisms, which, with 

 beneficent or fatal results, assist everywhere chiefly in 

 the larger organisms in the struggle for existence. 

 It is, moreover, only a logical inference that if living 



1 ' Critiques and Addresses,' p. 233. 



