AIR-GERMS AND SPONTANEOUS GENERATION. 91 

 AIEr-GEEMS AXD SPONTANEOUS GENERATION. 1 



By P. SCnUTZENBEEGER. 



fTHrlE question of the origin of ferments is intimately connected with 

 -I- that of spontaneous generation. In fact, from the time of Van 

 Helmont and others, who, even in the seventeenth century, gave direc- 

 tions for the production of mice, frogs, eels, etc., the partisans of this 

 mode of generation have, by the progress of the tendency to examine 

 into the causes of things, been driven from the larger animals or plants 

 visible to the naked eye, to the smallest living productions, which we 

 can observe only by the aid of the microscope. But ferments are 

 found among these inferior microscopic organisms. liecli, a member 

 of the Academy of Cimento, showed that the worms in putrefied flesh, 

 which were at first thought to be of spontaneous origin, are only the 

 larvae from the eggs of flies, and that all that was necessary, to pre- 

 vent entirely the birth of these larva?, was to surround the decompos- 

 ing meat with fine gauze; he was the first to ascertain that parasitic 

 animals are sexual and able to lay eggs. 



The invention of the microscope, and the numerous observations by 

 which it was followed, toward the end of the seventeenth, and the 

 commencement of the eighteenth century, gave fresh impulse to the 

 doctrine of spontaneous generation, which had lost all credit in ques- 

 tions concerning the origin of living beings of a higher order. 



The question now was how to explain the origin of the various 

 living productions, revealed by the microscope in infusions of vege- 

 table and animal substances, among which no apparent symptom of 

 sexual generation could then be found. 



The subject was studied for the first time in a scientific manner by 

 Xeedham, who published, in 1*745, in London, a work on this subject. 

 This observer did for infusoria what had already been done for the 

 higher organisms. He protected, or rather endeavored to protect, 

 vegetable or animal infusions from the action of germs, seeds, or any 

 other agents of multiplication which could come from without. At 

 the same time he destroyed by a physical agent, heat, the germs which 

 might be supposed to exist beforehand in the liquid. Under these 

 conditions, either living beings will be produced in the midst of the 

 infusion, or none will be found there ; in the former case, it must be 

 admitted that these organisms are developed in the medium which is 

 suitable to them, without the intervention of any germ ; in the second, 

 that the doctrine of spontaneous generation is false. In reality, the 

 question can only be resolved in this manner, and all experimenters 



1 Abridged from " Schiitzenbergcr on Fermentations," No. XX. of the " International 

 Scientific Series." 



