286 RELATION OF FORESTS TO THE 



If a little decaying cheese, a decaying orange, and a decaying pear 

 be exposed to the air they may be found after a time covered with 

 mould ; and microscopic examination will show the three moulds to 

 be different each from the others. How may this be accounted for 1 

 Observation fails us ; we are thrown upon reason. Nobly have several 

 students of natural history endeavoured to extort from Nature an 

 answer to the question — How do germs first originate ? and Nature, 

 ever truthful, has truthfully replied to her questioners, but the reply 

 has always shown that the question was not so expressed as to elicit 

 by an explicit answer to it the information svhich was desired. It is 

 thus that I look at the experiments which have been made in con- 

 nection with what has conventionally but unscientifically been called 

 spontaneous genei'ation. And whilst awaiting patiently, and with 

 deep interest, the devising and application of a testing experiment— 

 which shall finally close all controversy — I take up the question I 

 have stated : How has the mould been produced, and that in three 

 difi'erent forms 1 



There are three solutions of the problem which at once offer them- 

 selves ; and these are not necessarily antagonistic to each other : it 

 may be the case that each and all of them may be correct. It may 

 have been the case, for aught we know to the contraiy, that by 

 chemical action, or this in some one or other of its correlated forms, 

 the decomposed organic matters which were the subjects of experi- 

 ment have been resolved into the germs of these moulds ; it may, for 

 aught we know to the contrary, have been the case that there were 

 germs of mould floating in the atmosphere, which alighted on the 

 decaying cheese, orange, and pear, and there germinated, the difi'erent 

 forms they took being determined by differences in the conditions in 

 which they were placed on these difi'erent substances ; or it may have 

 been the case, for aught we know to the contrary, that germs of all 

 the three species of mould, and many germs of other genera of organic 

 structures were floating in the atmosphere, but of these only those 

 which found in the decaying masses an appropriate soil and con- 

 dition of growth germinated there, and grew and brought forth fruit. 



These several suppositions are not necessarily antagonistic ; but 

 the last is the only one in entire harmony, — or, if that form of ex- 

 pression be deemed too sweeping, the one most in accordance, — 

 with what has been observed in regard to the difi'usion of more 

 highly organised vegetable forms. 



It is of these I have to speak, and I employ what has been said not 

 as an argument but as an illustration. 



