390 



GERM THEORY AND SPONTANEOUS GENERATION. 



kept sweet in air-tight vessels for any length 

 of time does not disprove the spontaneous gen- 

 eration of bacteria, since the presence of air 

 may be the condition of the operation of the 

 generative elements. Dr. Bastian does not be- 

 lieve oxygen to be necessary for the develop- 

 ment of bacteria. In answer to the objection 

 by Professor Huxley that the reliability of his 

 experiments which gave bacteria in hermeti- 

 cally closed flasks is disproved daily by the mil- 

 lions of air-tight cans in which meats and fruits 

 are kept perfectly sweet, he explained the pres- 

 ervation of canned meats and vegetable sub- 

 stances on another theory. He assumed that 

 fermentation does begin in such cans, but that 

 it is accompanied by the formation of gases, 

 whose pressure arrests the further development 

 of the incipient life. He asserted that the with- 

 drawal of the air in closed vessels would favor 

 the fermentation of their organic contents. 

 The idea of the pressure of gases checking and 

 stifling infusorial life in the cans is shown to 

 be erroneous by experiments of piercing them 

 under water. This had been often done by 

 Tyndall with tins, some of which had been 

 kept in the Royal Institution for sixty- three 

 years ; in every case he noticed a sucking in 

 of the water into the hole instead of an escape 

 of gases. He also subjected glasses containing 

 infusions of beef, mutton, hay, and turnip to 

 strong air-pressure, placing them in iron bot- 

 tles to protect them and bringing upon them a 

 pressure of ten to twenty -seven atmospheres ; 

 when he took them out at the end often days, 

 they were swarming with infusoria. In his 

 present experiment Tyndall expected to show 

 that the air was the vehicle of the germs of 

 fermentation, and not simply the condition of 

 generation, by dividing the flasks into two 

 groups, and opening those of one group in an 

 atmosphere which he had reason to suppose 

 was laden with bacterial germs, and those of 

 the other in the pure air of the glaciers, which 

 he supposed was almost free from infusorial 

 life. The one set of flasks, twenty-three in 

 number, he opened in a hay-loft. The active 

 agency of hay in disseminating the germs of 

 putrefaction is shown from the fact that, of a 

 number of flasks opened in the Royal Institu- 

 tion in 1876, only 42 per cent, were infected, 

 while of a number opened in 1877, where a 

 quantity of hay was carried into the room, 68 

 per cent, putrefied. He expected that the in- 

 flow of this germ-charged air, which rushed in 

 when the sealed ends were snipped off, would 

 be enough to ferment the infusions. The 

 twenty-seven others he opened with many pre- 

 cautions, on a ledge overhanging the Aletsch 

 glacier not far off, about 200 feet above the 

 hay-loft, on the edge of a precipice about 1,000 

 feet high facing northeast toward the snow- 

 fields and snow-caps of the Bernese Oberland. 

 ie wind was from the northeast. Standing 

 cautiously to the leeward, so that no germinal 

 particle should be blown from his clothes or 

 body into the mouth of the opened flask, and 



first heating the pliers with which he opened 

 the flasks in order to destroy any organic germs 

 which might cling to them, he snipped off the 

 necks of the twenty- seven flasks, and held them 

 in this mountain air, which had been some 

 time free from contact with vegetable or animal 

 matter. After thus charging the two sets of 

 flasks with different kinds of air, he suspended 

 them with their necks open over a stove in a 

 temperature ranging from 50 to 90 F. In 

 three days twenty -one out of the twenty- 

 three flasks opened in the hay-loft showed the 

 presence of bacteria, the other two remaining 

 clear. Every one of the other group, which 

 had been opened in the pure air blowing across 

 the mountain tops and glaciers, remained as 

 pellucid as ever at the end of three weeks, the 

 flasks being so shaped that no germ from the 

 kitchen air could enter the narrow necks in 

 the position in which they were placed. 



It is a matter of high importance to the ex- 

 perimentalist to know the temperature, if it is 

 below 212 F., which is necessary to destroy 

 bacterial life, or the death-point of the bacteria 

 and their germs. Or, since the only practicable 

 method of sterilizing infusions is by boiling, 

 the length of time required in killing the infu- 

 soria and their germs at that temperature re- 

 quires to be known. The developed soft bac- 

 teria in fermenting liquids are unable to survive 

 exposure to a temperature of from 140 to 150 

 for a long time ; the active bacteria both of 

 fermentation and putrefaction can be killed by 

 two or three minutes' boiling. But the dor- 

 mant bacterial germs which float in the air, 

 Professor Tyndall's experiments go to show, 

 are much more obdurate. He found four hours 

 the usual limit of their endurance of the boiling 

 temperature, although their tenacity of life 

 was very variable. In a single case the germs 

 were not destroyed by eight hours' boiling. 

 After infecting the air of the laboratory with 

 dried hay, and charging ten sets of flasks with 

 turnip infusions, he boiled them for periods 

 varying by intervals of fifteen minutes, and 

 ranging from fifteen minutes to three hours, 

 except the tenth, which was boiled four hours. 

 All but the last yielded life. Proceeding in the 

 same way with a cucumber infusion, he obtained 

 the same result. Beef and mutton infusions 

 infected in the same way putrefied alter being 

 exposed to five hours' boiling. These germs 

 were those of the hay bacterium {Bacillus sub- 

 tilis). Tyndall ascribes this long resistance to 

 heat to the desiccation and hardening of the 

 substance of these bacterial seeds. 



Dr. Bastian, a physician and biologist, has 

 obtained results in his experiments, extending 

 through a long series of years, which are dia- 

 metrically opposed to those of Pasteur and 

 Tyndall. In a book called " The Beginnings of 

 Life," published in 1872, he brought forward 

 arguments, based on his own observations and 

 those of many other experimenters both of the 

 present and of the past, to show that the lowest 

 forms of infusorial life are spontaneously gen- 



