4 . BIOLOGY AND TECHNIQUE 



questions, namely, that of the origin of these minute living beings, was 

 being discussed with much passion by the scientific world. It was held 

 by the conservative majority that the microorganisms described by 

 Leeuwenhoek and others after him, were produced by spontaneous 

 generation. The doctrine of spontaneous generation, in fact, was 

 solidly established and sanctified by tradition, and had been applied 

 in the past not alone to microorganisms.' And it must not be forgotten 

 that without the aid of our modern methods of study, satisfactory 

 proof for or against such a process was not easily brought. 



Needham, who published in 1749, had spent much time in fortify- 

 ing his opinions in favor of spontaneous generation by extensive ex- 

 perimentation. He had placed putrefying material and vegetable in- 

 fusions in sealed flasks, exposing them for a short time to heat, by 

 immersing them in a vessel of boiling water, and had later shown them 

 to be teeming with microorganisms. He was supported in his views 

 by no less an authority than Buffon. The work of Needham, however, 

 showed a number of experimental inaccuracies which were thoroughly 

 sifted by the Abb6 Spallanazani. This investigator repeated the ex- 

 periments of Needham, employing, however, greater care in sealing his 

 flasks, and subjecting them to a more thorough exposure to heat. 

 His results did not support the views of Needham, but were answered 

 by the latter with the argument that by excessive heating he had pro- 

 duced chemical changes in his solutions which had made spontaneous 

 generation impossible. 



The experiments of Schulze, in 1836, who failed to find living organ- 

 isms in infusions which had been boiled, and to which air had been 

 admitted only after passage through strongly acid solutions, and similar 

 results obtained by Schwann, who had passed the air through highly 

 heated tubes, were open to criticism by their opponents, who claimed 

 that chemical alteration of the air subjected to such drastic influences, 

 had been responsible for the absence of bacteria in the infusion. Similar 

 experiments by Schroeder and Dusch, who had stoppered their flasks 

 with cotton plugs, were not open to this objection, but had also failed to 

 cohvince. The question was not definitely settled until the years im- 



1 Valleri-Radot, in his life of Pasteur, stated that Van Helmont, in the six- 

 teenth century, had given a celebrated prescription for the creation of mice 

 from dirty linen and a few grains of wheat or pieces of cheese. During the centu- 

 ries following, although, of course, such remarkable and amusing beliefs no longer 

 held sway, nevertheless the question of spontaneous generation of minute and 

 structureless bodies, like the bacteria, still found learned and thoughtful partisans. 



