344 FRAGMENTS OF SCIENCE 



erated." The inference, on the face of it, is an unwar- 

 ranted one. But while as matter of logic it is inconclusive, 

 as matter of fact it is chimerical. London air is as surely 

 charged with the germs of bacteria as London chimneys 

 are with smoke. The inference just referred to is com- 

 pletely disposed of by the simple question: "Why, when 

 your sterilized organic infusion is exposed to optically 

 pure air, should this generation of life de novo utterly 

 cease ? Why should I be able to preserve my turnip-juice 

 side by side with your saline solution for the three hun- 

 dred and sixty -five days of the year, in free connection 

 with the general atmosphere, on the sole condition that 

 the portion of that atmosphere in contact with the juice 

 shall be visibly free from floating dust, while three days' 

 exposure to that dust fills it with bacteria ? ' ' Am I over- 

 sanguine in hoping that as regards the argument here set 

 forth he who runs may read, and he who reads may under- 

 stand? 



We now proceed to the calm and thorough considera- 

 tion of another subject, more important if possible than 

 the foregoing one, but like it somewhat difficult to seize 

 by reason of the very opulence of the phraseology, logical 

 and rhetorical, in which it has been set forth. The sub- 

 ject now to be considered relates to what has been called 

 "the death-point of bacteria." Those who happen to be 

 acquainted with the modern English literature of the ques- 

 tion will remember how challenge after challenge has been 

 issued to panspermatists in general, and to one or two 

 home workers in particular, to come to close quarters on 

 this cardinal point. It is obviously the stronghold of the 

 English heterogenist. "Water," he says, "is boiling mer- 

 rily over a fire when some luckless person upsets the ves- 



