BIOLOGY. 281 



of the opposite opinion, under the inspection of the Commission, 

 will abundantly suffice to satisfy most unprejudiced minds. But, 

 as M. Balard observes in his report, " as nothing is so abundant 

 as vague and inexact observations, conclusions deduced, at least 

 apparently, from direct experiments, have never been wanting 

 to support this doctrine of spontaneous generation." 



On the 22d of June, M. Pasteur commenced his series of experi- 

 ments, in presence of the Commission and of his antagonists, 

 MM. Pouchet, Joly, and Musset. He first exhibited to the meet- 

 ing three glass flaslvs, filled with air collected on the Montanvert 

 in 1860, and showed that, even after the lapse of four years, the 

 solution of yeast contained in them had undergone no alteration, 

 and was perfectly transparent. The analysis of the air of one of 

 these flasks showed that it contained no cai-bonic acid, and that 

 the normal quantity of ox3'gen (21 per cent.) was still present in 

 it. Another flask was broken at the neck in such a manner that its 

 orifice, directed upward, was less than one square centimetre. 

 On Saturday, the 25th, five loose flakes of mycelium had already 

 made their appearance in it, and these subsequently became con- 

 siderably developed. Thus, to the single flask which MM. Joly 

 and Musset had declared would suffice to convince them, M. Pas- 

 teur might have added many others, for of the seventy-three ves- 

 sels which he brought from the Montanvert and the Jura, he has 

 still a great number untouched, none of which exhibit any altera- 

 tion. 



We now come to the description of M. Pasteur's series of experi- 

 ments for the establishment of his view. Sixty glass flasks, each 

 capable of containing from two hundred and titty to three hundred 

 cubic centimetres, were filled up to about one-third with a fer- 

 mentescible liquid, prepared by boiling yeast in water in the pro- 

 portion of one hundred grammes to each litre. The necks of the 

 flasks wei-e then drawn out into a fine tube, the liquid was boiled 

 for about two minutes, and then each of the balloons was hermet- 

 ically sealed. Fil'ty-six of the flasks bore this treatment without 

 damage, four others were charged with the same liquid, and 

 treated in the same waj^ except that their necks were merely 

 drawn out and twisted, without being closed. 



The next step in the experiments consisted in the fracture of the 

 narrow necks of the flasks, so as to allow the air to rush into the 

 Interior, which it did with a whistling sound. This operation was 

 performed by M. Pasteur, with all the precautions which he has 

 always particularly insisted on. One of the flasks was found to 

 have been imperfectly closed in the first instance, so that it had 

 been gradually filled with air ; it forms one of the first series of 

 nineteen filled in the amphitheatre of the Museum. A second 

 series of nineteen was filled with air on the outside of the dome of 

 the amphitheatre, at its highest point; and the remaining eighteen, 

 forming a third series, were opened at Bellevue, in the middle of 

 a grass plot, near a clump of large poplars. After the access of 

 air, the slender tubes of the necks were closed by the seolipj'le. 

 The whole of the flasks were then arranged in a convenient place 

 in the Museum, together with three test-glasses, filled with the 

 2-k* 



