126 Evolution of Vegetal Life. 



much time and thought and careful experiment have been 

 given. 



Not many years ago it was supposed that the develop- 

 ment of infusoria in water, in which organic matter had 

 been steeped ; the swarming of animal and vegetable life in 

 decaying organic matter of all kinds, and where no organic 

 matter was known to exist, and great caution had been used 

 in experimentation, and other similar facts, were proof 

 positive that such life may even now be generated sponta- 

 neously. But then followed an enormous increase in the 

 precision and care with which experiments could be con- 

 ducted, and it was believed by most that when all access of 

 the germ-laden air had been made impossible, and other es- 

 sential conditions had been fulfilled, no such generation oc- 

 curred. Subsequent investigation made this again uncertain. 

 I have an impression that some one has said, if not, some 

 one will say, that the struggle here is like that between 

 the manufacturers of big guns, and the builders of mail-clad 

 vessels. As to spontaneous generation at the present time, 

 we can hardly dp more than render the Scotch verdict, 

 "not proven." But if it does not now occur, it does not 

 therefore follow that in the long-buried past the conditions 

 may not have been such as to have permitted this. 



In this connection, the theory that the parts of an individ- 

 ual, such as a tree or the individual cells of even complex 

 organisms, may have some sort of independent existence, is 

 most interesting. 



Supposing the development theory to be correct, it is to 

 be assumed that the earliest forms of vegetable and animal 

 life must have been the simplest mere albuminous mat- 

 ter. No such forms are found in the geological record : it 

 is impossible that they should be, their substance and or- 

 ganization (if we may use such a term) were such that they 

 must inevitably be annihilated by time and mechanical ac- 

 tion. Moreover, all the earlier rocks appear to have been 

 exposed to such heat and pressure as must unquestionably 

 have destroyed much more elaborated tissues than those first 

 formed. Even should we ever obtain access to that portion 

 of the record now concealed in the bowels of the earth, or 

 under the waters of the sea, there is scarcely a possibility 

 that we should find evidence of the earliest forms of life. 

 Moreover, we could not expect to find a regular series of 

 forms. Between those deposits in which vegetable remains 



