loo THE POPULAR SCIENCE MONTHLY. 



These facts led M. Pasteur to make researches on the comparative 

 action of temperature on the fecundity of the spores of the mucidines, 

 and of the germs which exist suspended in the atmosphere. 



The following is, in few words, the method followed by him : He 

 passed a small portion of asbestos over the small heads of the moulds 

 which he wished to study ; he then placed this asbestos, covered with 

 spores, in a small glass tube, which he introduced into a U-tube 

 (Fig. 4) of larger diameter, in which the smaller tube could move 

 freely ; one of the extremities of the U-tube is joined by India-rubber 

 to a metal tube in form of a T, with stopcocks. One of these cocks 

 communicated with the air-pump, another with a red-hot platinum 

 tube. The other extremity has an India-rubber tube which is con- 

 nected with the flask into which the spores are to be introduced ; this 

 flask is hermetically sealed, and has been filled with calcined air, 

 and suitable nutritious liquid previously raised to the boiling-point. 

 Finally, the U-tube dips into a bath of oil, of common water, or salt- 

 water, according to the temperature which we wish to attain. Be- 

 tween' the U-tube and that of platinum, there is a drying-tube with 

 sulphuric pumice-stone. When all the apparatus which precedes the 

 platinum tube has been tilled with calcined air, and the spores have 

 been maintained at the desired temperature for a sufficient time, which 

 maybe varied at pleasure, the point of the flask is broken with a blow 

 of a hammer, without unfastening the India-rubber connecting-pieces 

 which attach the flask to the U-tube ; then inclining to a proper angle 

 this latter tube, when removed from its bath, the asbestos with its 

 spores is slipped into the flask. The flask is then hermetically sealed, 

 and is carried to the stove at 68 to 86 Fahr. The experiment with 

 the dust from the air is also made in the same manner with asbestos. 



Without any humidity, the fecundity of the spores of Penecillium 

 glaucum is preserved up to 248 Fahr., and even a little above 257 

 Fahr. It is the same with the spores of the other common mucidines. 

 At 266 Fahr., the power of developing or multiplying is destroyed in 

 all of them. The limits are the same for the dust from the air. 



In all these careful experiments, the most scrupulous precautions 

 were taken to prevent the access of the slightest portion of common 

 air. But, say the partisans of heterogenesis, if the smallest portion 

 of common air develops organisms in any infusion whatever, it must 

 necessarily be the case that, if these organisms are not spontaneously 

 generated, there must be germs of a multitude of various productions 

 in this portion of common air, however small it may be ; and, if things 

 were so, the ordinary air would be loaded with organic matter, which 

 would form a thick mist in it. 



M. Pasteur has shown that there is a srrcat deal of exasroeration in 

 the opinion that even the smallest quantity of air is sufficient to de- 

 velop multitudes of organisms ; that, on the contrary, there is not in 

 the atmosphere a continuous cause of these so-called spontaneous gen- 



