176 Prof. J. Tyndall on the [Jan. 13, 



laid — that of hermetically sealed tubes. On the 6th of last April a dis- 

 cussion on the " G-erin-Theory of Disease" was opened before the Patho- 

 logical 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 forward against the theory on 

 that occasion. The following important summary of these was then given 

 by Dr. Bastian : — "With the view of settling these questions, therefore, we 

 may carefully prepare an infusion 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 blowpipe-flame, we may boil the fluid, seal the vessel 

 during ebullition, and, keeping it in a warm place, may await the result, 

 as I have often done. After a variable time, the previously heated fluid 

 within the hermetically sealed flask swarms more or less plentifully with 

 Bacteria and allied organisms." 



Previous to reading this statement the author had operated upon 16 tubes 

 of hay- and turnip-infusions, and upon 21 tubes of beef, mackerel, eel, 

 oyster, oatmeal, malt, and potato, hermetically sealed while boiling, not by 

 the blowpipe, but by the far more handy spirit-lamp flame. In no case 

 was any appearance whatever of Bacteria or allied organisms observed. 

 The perusal of the discussion just referred to caused the author to turn again 

 to muscle, liver, and kidney, with a view of varying and multiplying the 

 evidence. Fowl, pheasant, snipe, partridge, plover, wild duck, beef, 

 mutton, heart, tongue, lungs, brains, sweetbread, tripe, the crystalline 

 lens, vitreous humour, herring, haddock, mullet, codfish, sole, were all 

 embraced in the experiments. There was neither mistake nor ambiguity 

 about the result. One hundred and thirty-nine of the flasks operated on 

 were submitted to the Fellows ; and not one of this cloud of witnesses 

 offered the least countenance to the assertion that liquids within flasks, 

 boiled and hermetically sealed, swarm, subsequently, more or less plenti- 

 fully with Bacteria and allied organisms. 



The evidence furnished by this mass of experiments, that Dr. Bastian 

 must have permitted errors either of preparation or observation to invade 

 his work, is, it is submitted, very strong. But to err is human ; and m 

 an inquiry so difficult and fraught with such momentous issues, it is not 

 error, but the persistence in error by any of us for dialectic ends that is 

 to be deprecated. The author shows by illustrations the risks of error 

 run by himself. On the 21st of October he opened the back door of a 

 case containing six test-tubes filled with an infusion of turnip which had 

 remained perfectly clear for three weeks, while three days sufficed to 

 crowd six similar tubes exposed to mote-laden air with Bacteria. With a 

 small pipette he took specimens from the pellucid tubes, and placed them 

 under the microscope. One of them yielded a field of Bacterial life, 

 monstrous in its copiousness. For a long time he tried vainly to detect 

 any source of error, and was perfectly prepared to abandon the unvarying 

 inference from all 'the other experiments, and to accept the result as a 



