486 THE POPULAR SCIENCE MONTHLY. 



weather is favorable to putrefaction. We open our box at the Bel- 

 Alp, and count out fifty-four flasks, with their liquids as clear as fil- 

 tered drinking-water. In six flasks, however, the infusion is found 

 muddy. We closely examine these, and discover that every one of 

 them has had its fragile end broken off in the transit from London. 

 Air has entered the flasks, and the observed muddiness is the result. 

 My colleague knows as well as I do what this means. Examined 

 with a pocket-lens, or even with a microscops of insufficient power, 

 nothing is seen in the muddy liquid ; but regarded with a magnifying 

 power of a thousand diameters or so, what an astonishing appearance 

 does it present ! Leeuwenhoek estimated the population of a single 

 drop of stagnant water at 500,000,000 : probably the population of a 

 drop of our turbid infusion Avould be this many times multiplied. The 

 field of the microscope is crowded with organisms, some wabbling 

 slowly, others shooting rapidly across the microscopic field. They 

 dart hither and thither like a rain of minute projectiles ; they pirou- 

 ette and spin so quickly round, that the retention of the retinal im- 

 pression transforms the little living rod into a twirling wheel. And 

 yet the most celebrated naturalists tell us that they are vegetables. 

 From the rod-like shape which they so frequently assume, these 

 organisms are called bacteria a term, be it here remarked, which 

 covers organisms of very diverse kinds. 



Has this multitudinous life been spontaneously generated in these 

 six flasks, or is it the progeny of living germinal matter carried into 

 the flasks by the entering air? If the infusions have a self-gen erative 

 power, how are the sterility and consequent clearness of the fifty-four 

 uninjured flasks to be accounted for? My colleague may urge and 

 fairly urge that the assumption of germinal matter is by no means 

 necessary; that the air itself may be the one thing needed to wake 

 up the dormant infusions. We will examine this point immediately. 

 But I would meanwhile remind my friend that I am working on the 

 exact lines laid down by our most conspicuous heterogenist. He dis- 

 tinctly affirms that the withdrawal of the atmospheric pressure above 

 the infusion favors the production of organisms; and he accounts for 

 their absence in tins of preserved meat, fruit, and vegetables, by the 

 hypothesis that fermentation has begun in such tins, that gases have 

 been generated, the pressure of which has stifled the incipient life and 

 stopped its further development. 1 This is Dr. Bastian's theory of 

 preserved meats. Its author has never, to my knowledge, pierced a 

 tin of preserved meat, fruit, or vegetable, under water with a view 

 of testing its truth. Had he done so, he would have found it erro- 

 neous. In well-preserved tins I have invariably found, not an out- 

 rush of gas, but an inrush of water, when the tin was perforated. 

 I have noticed this recently in tins which have lain perfectly good for 

 sixty-three years in the Royal Institution. Modern tins, subjected to 



1 "Beginnings of Life," vol. i., p. 418. 



