PROGRESS OF MICROSCOPICAL SCIENCE. 1-17 



within it to be laclcu with floating matter. On the 13th it was again 

 cxaminetl. Before the beam entered, and after it quitted the case, its 

 track was vivid in the air, but witliin the case it vanished. Three 

 days of quiet sufficed to cause all the floating matter to be deposited 

 on the sides and bottom, where it was retained by a coating of 

 glycerine, with which the interior surface of the case had been pur- 

 posely varnished. The test-tubes were then filled through the i:)ipette, 

 boiled for five minutes in a bath of brine or oil, and abandoned to the 

 action of the moteless air. During ebullition aqueous vapoiu' rose 

 from the liquid into the chamber, where it was for the most part 

 condensed, the uncondcnscd portion escaping, at a low temperature, 

 through the bent tubes at the top. Before the brine was removed 

 little stoppers of cotton-wool were inserted in the bent tubes, lest the 

 entrance of the air into the cooling chamber should at first be forcible 

 enough to carry motes along with it. As soon, however, as the 

 ambient temperature was assumed by the air within the case, the 

 cotton-wool stopi)ers were removed. Wo have here the oxygen, 

 nitrogen, carbonic acid, ammonia, aqueous vapour, and all the other 

 gaseous matters which mingle more or less with the air of a great 

 city. We have them, moreover, ' untortured ' by calcination and 

 unchanged even by filtration or manipulation of any kind. The 

 question now before us is, Can air thus retaining all its gaseous mix- 

 tures, but self-cleansed from mechanically suspended matter, produce 

 putrefaction ? To this question both the animal and vegetable 

 worlds retui-n a decided negative. Among vegetables exiieriments 

 have been made with hay, turnips, tea, coffee, hops, repeated in 

 various ways with both acid and alkaline infusions. Among animal 

 substances are to be mentioned many experiments with urine ; while 

 beef, mutton, hare, rabbit, kidney, liver, fowl, pheasant, grouse, had- 

 dock, sole, salmon, cod, turbot, mullet, herring, whiting, eel, oyster, 

 have been all subjected to experiment. The result is that infusions 

 of these substances exposed to the common air of the Eoyal Insti- 

 tution laboratory, maintained at a temperatm-e of from 60'^ to 70° 

 Fahr., all fell into putrefaction in the course of from two to four 

 days. No matter where the infusions were placed, they were infallibly 

 smitten. The number of the tubes containing the infusions was 

 multiplied till it reached six hundi'cd, but not one of them escaped 

 infection. In no single instance, on the other hand, did the air, 

 which had been proved moteless by the searching beam, show itself 

 to possess the least power of producing Bacterial life or the associated 

 phenomena of putrefaction. The j)ower of developing such life in 

 atmospheric air, and the power of scattering light, are thus proved to 

 be indissolubly united." 



Now to this lecture Dr. Bastian published a very intemperate 

 reply, couched in language entirely unbefitting a follower of truth 

 alone.* In this he cites at length the names of a series of authors 

 who agree with him, among whom wo find those of Scluoann and 

 Pasteur. He alleges that Professor Tyndall used infusions which 

 were not strong enough, and that he did not boil them long 

 * ' Brit. IMed. Jounuil,' Fob. 5. 



