ATMOSPHERE IN RELATION TO PUTEEEACTION AND INFECTION. 
69 
ment. In view of the foregoing calculation it, however, expresses the soberest fact 
Indeed, taking the word myriad in its literal sense of ten thousand, it would be simple 
bathos to apply it to the multitudinous germs of our air. 
§ 27. Some Experiments of Pasteur and their Belation to Bacterial Clouds. 
Quite recently I had occasion to refresh my memory of Pasteur’s paper published in the 
‘ Annales de Chimie ’ for 1862. The pleasure I experienced on first reading it was revived 
by its reperusal. Clearness, strength, and caution, with consummate experimental skill 
for their minister, were rarely more strikingly displayed than in this imperishable essay. 
Hence it is that during recent discussions, in which this and other labours of the highest 
rank met with such scant respect, those in England most competent to judge of the 
value of scientific work never lost faith in the substantial accuracy of Pasteur. One 
striking example of his penetration has an immediate bearing on the conclusion regarding 
Bacterial clouds, independently drawn by me from the deportment of the tray of one 
hundred tubes. On the 28th of May, 1860, Pasteur opened, on an uncovered terrace a 
few metres above the ground, four flasks containing the water of yeast. Nothing 
appeared in any of them until the 5th of June, when a small tuft of mycelium was 
observed in one of them. On the 6th a second tuft appeared in another flask; the two 
remaining flasks remained intact and without organisms. On the 20th of July he 
opened, in his own laboratory, six flasks containing water of yeast. Four of them 
remained perfectly intact, while two of them became promptly charged with organisms. 
Pasteur infers from these observations the non-continuity of the cause to which so-called 
spontaneous generation is due. This inference is quite in accord with the notion of 
Bacterial clouds suggested by my observations. Pasteur, in fact, sometimes opened 
his flask in the midst of a Bacterial cloud and obtained life, sometimes in the interspace 
between two clouds, and obtained no life. 
Not with a view of repeating this observation, which had been forgotten, but for another 
reason, I opened on the 6th of January last a number of hermetically sealed tubes in 
one and the same room of the Koyal Institution. The names of the infusions contained 
in the tubes, the date of sealing them up, their condition before opening on the 6th, 
and their appearance six days subsequently on the 12th are given in the accompanying 
statement. I chose for these observations tubes which contained a little liquid in their 
drawn-out portions. In every case the motion of this liquid, when the tube was broken, 
indicated a violent inrush of air. 
Infusion. Date of sealing. Appearance, Jan. 12. 
Grouse Nov. 27th Clear . . Clear. 
Sole 17th „ . . Turbid. 
Turnip No. 1 Oct. 5th ,, . . Penicillium on surface. 
Turnip No. 2 „ . . Clear. 
Hay „ „ „ . . Mycelium at bottom. 
Wild Duck Nov. 12th „ . . Turbid. 
l 2 
