230 PROGRESS OF MICROSCOPICAL SCIENCE. 



pressure of the atmosphere, obtained by sealing flasks hermetically in 

 ebullition, after the mode suggested by Dr. Bastian, materially affected 

 the results. At the conclusion of the paper Dr. E. Angus Smith.F.E.S., 

 said that he was glad to see such uniformity of results. His own ex- 

 periments, which were very numerous on a similar point, were made 

 differently, but were without exception proving the same. As to the 

 name of the substances in the air, he preferred germ : it involved no 

 theory. A germ may be considered that which germinates. Dust is 

 an equivocal expression, which may cause a popular error. Polarity 

 introduces a theory which is so entirely without basis that in our 

 present state of knowledge we may call the inference it presupposes 

 decidedly false. 



On the Origin of Bacteria, and on their relation to the Process of 

 Putrefaction. — Dr. Charlton Bastian lately read the following paper 

 before the Boyal Society : * — He says that in his now celebrated 

 memoir of 1862, M. Pasteur asserted and claimed to have proved (1) 

 that the putrefaction occurring in certain previously boiled fluids 

 after exposure to the air was due to the contamination of the fluids 

 by Bacteria, or their germs, which had before existed in the atmo- 

 sphere, and (2) that all the organisms found in such fluids have been 

 derived more or less immediately from the reproduction of germs 

 which formerly existed in the atmosphere. " The results of a long 

 series of experiments have convinced me that both these views are 

 untenable. In the first place, it can be easily shown that living 

 Bacteria, or their germs, exist very sparingly in the atmosphere, and 

 that solutions capable of putrefying are not commonly infected from 

 this source. It has now been very definitely ascertained that certain 

 fluids exist which, after they have been boiled, are incapable of giving 

 birth to Bacteria, although they continue to be quite suitable for the 

 support and active multiplication of any such organisms as may have 

 been purposely added to them. Amongst such fluids I may name 

 that now commonly known as 'Pasteur's solution,' and also one 

 which I have myself more commonly used, consisting of a simple 

 aqueous solution of neutral ammonic tartrate and neutral sodic 

 sulphate.^ When portions of either of these fluids are boiled and 

 poured into superheated flasks, they will continue quite clear for 

 many days, or even for weeks — that is to say, although the short 

 and rather narrow neck of the flask remains open, the fluids will not 

 become turbid, and no Bacteria are to be discovered when they are 

 submitted to microscopical examination. 



" But in order to show that such fluids are still thoroughly favour- 

 able media for the multiplication of Bacteria, all that is necessary is 

 to bring either of them into contact with a glass rod previously 

 dipped into a fluid containing such organisms. In about thirty-six 

 hours after this has been done (the temperature being about 80° F.), 

 the fluid, which had hitherto remained clear, becomes quite turbid, 



* 'Proceedings,' 141, 1873. 



t In the proportion of 10 grains of the former, and 3 of the latter, to 1 ounce 

 of distilled water. 



