362 Developmental History of Infusorial, Animal Life. 



form the indispensable condition for the development of the 

 eggs, it is only in the vessel containing such matter that the 

 eggs will develop ■ but why are they not also visible as eggs 

 in the other vessels ? Why are not the animalcules themselves 

 visible there as they were in the water examined by M. 

 Quatrefages ? 



My reply to Pouched s question is, that in all the vessels 

 ova had probably been deposited, but for lack of nourish- 

 ment, in five, they had quickly died. It is well known that in 

 all organized structures, disorganization rapidly sets in, unless 

 either some vegetable matter or a well- oxygenated medium be 

 ready at hand to carry the ova on to maturity. And as to their 

 not appearing in all the six vessels, I can only say that this does 

 not accord with my experience ; for upon exposing any number 

 of bottles to the same atmospheric influences, all have given 

 positive results, and I can only suppose that M. Pouchet either 

 made a very imperfect and cursory examination, or his micro- 

 scopic manipulation must have been greatly at fault. 



A few years ago an observation made by Oienkowski, the 

 botanist, seemed finally to settle the question of spontaneous 

 generation, and to place the matter beyond doubt, because it 

 caught nature in the act, so to speak, of spontaneously gene- 

 rating. Cienkowski's statement is as follows : — If a slice of 

 raw potatoe be allowed to decompose in a little water, it will 

 be found, after some days, that the starch cells have a peculiar 

 border, bearing* a strong resemblance to a cell-membrane. 

 This shortly turns out to be a real cell-membrane, and is 

 gradually raised above the starch grain, which then occupies 

 the position of a cell-nucleus. Thus, out of a grain of starch 

 a cell has been formed under the observer's eye. Inside this cell 

 little granular masses are developed, which begin to contract. 

 Finally, minute eel-like animalcules (a species of Anguillulidce) 

 are developed there, which bore their way through the cell- 

 wail into the water. 



Franke, in his report of this observation, which he says he 

 has verified, asks, "how is it possible to deny spontaneous 

 generation here ? Before our eyes a grain of starch becomes a 

 cell, in that cell are developed living forms, which bore their 

 way out." Again, Professor Ncegeli stated that he had been 

 baffled at first in the attempt to verify this observation, but 

 that after nearly a hundred trials he had succeeded • he appears 

 to have confirmed all the statements made by Cienkowski • but 

 if the phenomenon was of such rare occurrence, surely there must 

 have been some other explanation than that of spontaneous 

 generation. 



It seemed probable that error had crept in somewhere. 

 Cienkowski himself at length discovered the source of his own 



