306 BIOLOGY. [BOOK iv. 



sions. Some ovula may fall thereinto first* of all, be evolved, and 

 give birth to organisms which may multiply little by little. 

 Now in a fermentiscible liquid, we see at the outset a very thin 

 mucous pellicle forming on the surface. Then suddenly appear 

 in this pellicle many small lines, pale, immobile, ranged side 

 by side in a certain disorder. These lines have the form and 

 the diameter of bacteriums, and in effect, at the end of some 

 hours we see them take animation and become living bacteriums, 

 moving rapidly in a straight line. 



Gerard had noted, at the time of the appearance of proto- 

 organisms in the macerations, a certain evolutive order. In the 

 maceration of hay we see, the second day, specimens of the 

 bacterium termo simple, whose articulations augment little by 

 little. Then come monads, and at the end of fifteen days we 

 find trichods, colpods, the proteus tribe closing the series. 1 



F.-A. Pouchet has likewise demonstrated this evolution, % and 

 has drawn from it a whole theory. 2 According to him there 

 appears, first of all in the macerations, an ephemeral population 

 of vibrions and monads. These proto-organisms die. Their 

 debris and their dead bodies mount to the surface, fall asunder, 

 dissolve more or less, and all these detritus form a sort of 

 membrane, which organises itself anew, engendering ovula of 

 superior infusoria, microzoa with vibratile cilia. At certain 

 points of this pellicle, which Pouchet calls proligerous membrane, 

 we see granulations accumulate, mass themselves into a kind of 

 spheroidal nebulae. Then this nebulous substance becomes a true 

 ovular cell, surrounding itself with a translucid membrane, with 

 & bright zone. Finally this ovulum is evolved. We observe 

 therein the gyration of the content or vitellus, the formation of 

 the embryon, and the fifth day comes forth a rameciate. 



The same maceration gives, or does not give, birth to ciliated 

 microzoa, according as its pioligerous pellicle is more or less 

 thick. 



1 Gerard, Dictionrtairc d' Histoire Naturelle, art. GENERATION. 



2 F.-A. Poucbot, loc. cit., p. 110. 



