SPONTANEOUS GENERATION. 305 



meter, until the canal is completely blocked up. The 

 tongs with the fragment of severed neck being with- 

 drawn, the flask, with its contents diminished by evapo- 

 ration, is lifted from the oil-bath perfectly sealed 

 hermetically. 



Sixty such flasks filled, boiled, and sealed in the 

 manner described, and containing strong infusions of 

 beef, mutton, turnip, and cucumber, are carefully 

 packed in sawdust, and transported to the Alps. 

 Thither^ to an elevation of about 7,000 feet above the 

 sea, I invite my co-enquirer to accompany me. It is 

 the month of July, and the weather is favourable to 

 putrefaction. We open our box at the Bel-Alp, and 

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

 filtered drinking water. In six flasks, however, the in- 

 fusion 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 microscope 

 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 appear- 

 ance does it present I 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 would 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 pirouette and 

 spin so quickly round, that the retention of the retinal 

 impression transforms the little living rod into a 

 twirling wheel. And yet the most celebrated naturalists 



