4 BIOLOGY AND TECHNIQUE 



It was during this period also that one of the most fundamental 

 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 de- 

 scribed 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. 2 And it must not be 

 forgotten that without the aid of our modern methods of study, satis- 

 factory 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 

 experimentation. He had placed putrefying material and vegetable 

 infusions 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 Abbe Spallanzani. This investigator re- 

 peated the experiments 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 produced chemical changes in his solutions which had 

 made spontaneous generation impossible. 



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

 organisms 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 oppo- 

 nents, who claimed that chemical alteration of the air subjected to 

 such drastic influences had been responsible for the absence of bac- 

 teria in the infusion. Similar experiments by Schroeder and Dusch, 

 who had stoppered their flasks with cotton plugs, were not open to 



2 Valleri-Radot, in his life of Pasteur, states 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. 



