PROFESSOR TYN BALL'S RECENT RESEARCHES. 691 



as clear and cloudless at the present moment as they were upon the 

 day of their introduction; while twelve similar tubes, prepared at the 

 same time, in precisely the same way, and exposed to ordinary airfare 

 clogged with mycelium, mould, and bacteria. 



With regard to calcined air, a similar propagating glass was 

 caused to cover twelve other tubes filled with the same infusion. The 

 " glass " was exhausted and carefully filled with air, which had passed 

 through a red-hot platinum-tube, containing a roll of red-hot platinum- 

 gauze. Tested by the searching beam, the calcined air was found quite 

 free from floating mattei-. Not a speck has invaded the limpidity of 

 the infusions exposed to it, while twelve similar tubes, placed outside, 

 have fallen into rottenness. 



The experiments with calcined air took another form. Six years 

 ago, it was found that, to render the laboratory air free from floating- 

 matter, it was only necessary to permit a platinum-wire heated to 

 whiteness to act upon it for a sufficient time. Shades containing pear- 

 juice, damson-juice, hay and turnip juice, and water of yeast, were 

 freed from their floating matter in this way. The infusions were sub- 

 sequently boiled, and permitted to remain in contact with the calcined 

 air. They are quite clear to the present hour ; while the same infu- 

 sions, exposed to common air, became mouldy and rotten long ago. 



It has been aflirmed by other Avorkers on this question, that turnip 

 and hay infusions, rendered slightly alkaline, are particularly prone to 

 exhibit the phenomena of spontaneous generation. This was not found 

 in the present investigation to be the case. Many such infusions have 

 been prepared, and they have continued for months without sensible 

 alteration. 



Finally, with regard to infusions wholly withdrawn from air, a 

 group of test-tubes containing difierent infusions was boiled under a 

 bell-jar filled with filtered air, and from which subsequently the air 

 was removed as far as possible by a good air-pump. They are now as 

 pellucid as they were at the time of their preparation more than two 

 months ago, while a group of corresponding tubes exposed to the 

 laboratory air has all fallen into rottenness. 



There is another form of experiment on which great weight has 

 been laid ; that of hermetically-sealed tubes. On the 6th of last April, 

 a discussion on the " Germ-Theory of Disease " was opened before the 

 Pathological Society of London. The meeting was attended by many 

 distinguished medical men, some of whom were profoundly influenced 

 by the arguments, and none of whom disputed the facts brought for- 

 ward against the theory on that occasion. The following important 

 summary of these was given by Dr. Bastian : "With the view of 

 settling these questions, therefore, we may carefully prepare an infu- 

 sion from some animal tissue, be it muscle, kidney, or liver; we may 

 place it in a flask whose neck is drawn out and narrowed in the blow- 

 pipe-flame ; we may boil the fluid, seal the vessel during ebullition, 



