84 EXPERIMENTAL MICROSCOPY—SOMMERS. 
“and cut them into small pieces, sow these in an oleaginous soil, 
“sprinkle from day to day with water, taking care that the piece 
“of ground be exposed to the spring sun, and in eight days you 
“will see the earth strewn with little worms, which, being 
“nourished with milk diluted with water, will gradually increase 
“in size till they take the form of perfect serpents.’—Kercher 
Mund. Subterran. 
Redi determined to prove the recipe, and in doing so, exploded 
his friend’s theory. He says :— 
“Moved by the authentic testimony of this most learned 
“author, I have frequently tried the experiment, but I could 
“never witness the generation of those blessed snakelets made to 
“hand.’—Redi, Generat, Insectorum, 1686. 
Redi however found an abundant progeny of Maggots, which, 
being confined in a covered box, were ina short time transformed 
into flies. To Redi’s observations science is indebted for some of 
the earliest definite knowledge of the generation and metamor- 
phoses of insects. 
If one of the ablest men of his time, which Kercher undoubt- 
edly was, will to us appear at a disadvantage, because he too 
readily accepted a false theory, how ‘careful we should be lest 
our successors a century or so hence may be in a position to sub- 
ject our theories and experiments to the criticism of ridicule. 
The substitution of infusions of chopped hay ‘or turnips in water 
and exposure to sunlight, for chopped snakes, milk, and sunlight, 
is startlingly like a repetition of the old process, and is likely te 
be followed by equally satisfactory results. 
The revelations of the microscope in all that relates to the 
process of generation so far as positive facts are concerned, tend 
to prove the truth of the proposition that every living organism 
has been generated or produced by a pre-existing living organ- 
ism. The theory of spontaneous generation had fallen inte 
disregard until certain observations of Pouchet, put forward in 
the year 1847, caused its revival. Pouchet in his experiments 
seemed to show that certain infusorial animalcules were gene- 
rated spontaneously, but subsequent experiments ‘of Balbiani, in 
1861, demonstrated the existence of sexual generation in these 
