THE ORIGIN OF MICROBES 101 



living beings, however small and simple, ever origi- 

 nating in any other way than from germinal matter 

 which sprang from the same form of life ; and they 

 insist that the belief in the equivocal origin of 

 microbes is that last remnant of an old superstition, 

 which the light of science has not entirely banished. 

 In ancient times it was thought that serpents and 

 frogs originated from slime, that caterpillars were 

 generated from decayed leaves, vermin from filth, 

 and worms from spoiled meat. Now-a-days every 

 child knows that all these things are fables ; every 

 housewife knows by experience that no maggots 

 originate in meat if the blow-fly is prevented by a 

 wire-screen from entering and depositing its eggs. 

 They have learned, through careful covering, to keep 

 away the minute mould- spores, which settle with 

 other dust from the air, and which colonise on their 

 preserved fruits ; they know that trichina and tape- 

 worm only originate from raw or half-cooked pork, 

 in which these animals were already present in the 

 embryonic stage. Even the farmer no longer believes 

 that the grain rust (Puccinia graminis) originates 

 from chilling, but that it springs from spores which 

 are scattered by the barberry bushes (Berberis vul- 

 garis), or other fallen stalks, and that the blight may 

 be prevented in corn crops, if the seed (before sow- 

 ing) is steeped in a solution of iron sulphate or copper 

 sulphate, in order to kill the spores which cling to it. 1 

 Concerning microbes and their related ' fermenta- 

 tions/ the above-mentioned observations lead without 



1 See Dr. Griffiths' book, The Diseases of Crops, pp. 128-132 

 (Bell & Sons). 



