GERM THEORY AND SPONTANEOUS GENERATION. 



387 



the Continental coal fields, has increased so 

 much of late that it has become a competitor 

 with the English coal fields in some of the mar- 

 kets near it. The yield, which in 1854 was 

 only 2,800,000, was 4,000,000 tons in 1860, 

 double that amount in 1865, 12,461,000 tons 

 in 1871, 16,127,000 tons in 1873, and in 1876 

 reached 17,636,757 tons, a rate of production 

 which has since barely been sustained. 



GERM THEORY AND SPONTANEOUS 

 GENERATION. The recent investigations of 

 Pofessor Tyndull, Dr. Bastian, and other sci- 

 entists and physicians, from their different 

 results, have revived the ancient and oft-re- 

 turning question of spontaneous generation. 

 The examination of the phenomena of the 

 lowest forms of infusorial life is of great prac- 

 tical as well as scientific interest, and affects 

 pathology and medicine in as high a degree 

 as it pertains to the deep problem of the ori- 

 gin of life, since on its solution probably de- 

 pends the theoretical knowledge of the epi- 

 demic diseases which scourge the human race. 

 The doctrine of spontaneous generation was 

 prevalent in the early periods of science, and 

 there could not be a more natural conclusion, 

 one which must have prevailed even were it 

 not supported by the supreme authority of 

 Aristotle, when every pool was seen to swarm 

 and every decaying organic substance teemed 

 with active creatures which, in the light of the 

 older science, must have sprung into being 

 without preceding life. Redi, in the latter 

 part of the seventeenth century, first shook 

 the old belief by discovering that flies were 

 the progenitors of the maggots which appear 

 in putrid flesh, which he established by fast- 

 ening fine gauze over jars of meat, and ob- 

 taining maggots on the surface of the net on 

 which the flies swarmed, while the putrescent 

 meat within was free from them. Vallisnieri, 

 Schwammerdam, and Reaumur combated and 

 overthrew the doctrine of spontaneous genera- 

 tion. Yet the invention of the microscope 

 brought to the knowledge of the scientific 

 community the world of infusoria, of which 

 minute organisms it was difficult to predicate 

 the ordinary functions of life, and Buffon and 

 Needham, who was the first to experiment 

 with sealed infusions of organic extracts, and 

 who found that the infusions putrified, revived 

 in a new form the idea of the spontaneous 

 origin of life. Spallanzani afterward, by re- 

 peating the experiment of Needham with in- 

 fusions in flasks sealed during ebullition, with 

 the improvement of hermetically closing them 

 by melting their necks with the blowpipe, 

 which has since been the usual test in these 

 investigations, obtained no life, and was ena- 

 bled to contradict the doctrine of heterogenesis, 

 and Buffon's notion of organic molecules, al- 

 though his experiment was applied under con- 

 ditions which would ordinarily have yielded 

 infusoria, as was afterward shown by Wyman 

 and others. To obviate the objection that 

 there was not enough vitalizing oxygen in 



Spallanzani's flasks to sustain animal life, 

 Schulze, in 1836, supplied a sterilized organic 

 infusion with air passed through bulbs con- 

 taining sulphuric acid to destroy all germs ; 

 although he obtained no life, it was subse- 

 quently shown by Tyndall that the air globules 

 must be thoroughly broken up to prevent the 

 passage of germs, and when that is done water 

 is as good a sifting medium as the acid. 

 Schwann, Helmholtz, and Schroeder enlarged 

 the field of inquiry by discovering the organic 

 nature of all kinds of fermentation. In 1859 

 Pouchet, in his "Het6rog6nie," again resusci- 

 tated the doctrine of spontaneous generation. 

 Isolating sterilized organic substances, in the 

 same manner as Schwann and Schulze, and 

 supplying them with calcined air, he obtained 

 the bacteria of fermentation, and, enforced by 

 his brilliant dialectic, the old belief obtained a 

 new footing. 



Next, Pasteur applied his searching mind to 

 this subject. He confirmed the experiments 

 of Schwann and the others which were favor- 

 able to the germ theory. He further tested 

 the germ-bearing property of the air in differ- 

 ent positions and under different conditions, 

 and reached the conclusion that the germs 

 were not found in all airs, nor were they 

 uniformly distributed through the atmosphere 

 on the same spot. These experiments were 

 strongly confirmatory of this germ theory in 

 general. He succeeded in capturing and ex- 

 amining the floating particles of the atmos- 

 phere by the most delicate methods, and, on 

 microscopic scrutiny, found many of them to 

 be organic bodies, which, when he introduced 

 them into sterilized solutions, engendered in- 

 fusorial life in abundance. He performed the 

 experiment, repeated by Tyndall and described 

 below, of opening two sets of flasks of infu- 

 sions, one in the air of the glaciers and one in 

 an air which came directly in contact with or- 

 ganic life : of twenty flasks broken on the Mer 

 de Glace, near the Montanverfc, in Switzerland, 

 but one afterward showed signs of life; while 

 out of twenty charged with the air of the 

 plains below, eight became full of microscopic 

 creatures. The undisturbed air of the caves 

 under the Observatory of Paris he found des- 

 titute of generative properties. Pasteur's in- 

 vestigations were of the highest practical value, 

 as his conclusions were practically applied by 

 himself in the preservation of wine and beer, 

 the manufacture of vinegar, and, above all, in 

 the suppression of the destructive silkworm 

 disease. He showed that the spoiling of beer, 

 wine, etc., is the effect of another fermentation 

 caused by the floating germs of the air ; that 

 the true alcoholic fermentation, produced in 

 beer by the yeast-plant (Torula}, and in wine 

 by germs which adhere to the fruit and plant, 

 is the effect of depriving the organisms of air 

 by submersion, causing them to attack the su- 

 gar and in obtaining their nutriment from it to 

 liberate the alcohol. He traced the grape dis- 

 ease to germs transmitted through the air, and 



