18 Introduction. | Jan. 
forms of matter were originally combined to form a living being, and 
the sexual law substituted ; one or two pre-existing germs, either active 
or in a state of rest, being needful for the production of a new being. 
But, lastly, it is possible that all the foregoing laws may be in ope- 
ration, inasmuch as no one of them necessarily interferes with another. 
The evidence in favour of the doctrine of spontaneous gene- 
ration, is found in the appearance of certain obscure moving types, 
of infinitely small proportions, in decaying substances, notwithstanding 
every effort on the part of man to exclude the germs of life in any 
form. That in favour of the artificial production, by man, of the 
lowest living types, is of a still more dubious character. It consists 
in the fact that out of inorganic substances he has been able to make 
a few organic compounds, such as urea, butyric acid, &c.; but our 
readers will see clearly that to make an inanimate complex substance 
from other inanimate simple substances, though we may call the 
former “ organic ”’ (in consequence of their usual origin), and the lat- 
ter “inorganic,” is a process widely different from that of making a 
living, moving, sentient being. Still the latter is not impossible, and 
if man do succeed in making such a being, and it be endowed with 
animation by the Giver of Life, he will but have added to his responsi- 
bilities, as he every day multiplies them, by the acquisition of fresh 
knowledge. 
But having thus granted a fair hearing to the advocates of the 
“spontaneous generation” theory, and to those who propound the 
second doctrine, we feel bound to state that the evidence against 
both multiplies day by day. It is found, first, in the constantly 
accumulating proofs in favour of the parental law. One after another, 
types which were supposed to have been spontaneously generated, from 
insects down to infusoria, are found to exist as germs or ova, either in 
the water, in other living beings, in decaying bodies or animal sub- 
stances, or, as it has been recently shown by French and English 
observers, to an enormous extent in the atmosphere which we breathe. 
It has been proved, too, that the tenacity of life which these germs 
possess is very great ; enabling them to defy the hand of time or the 
destructive power of chemical and physical agencies, and these facts, 
coupled with the abnormal conditions under which such germs are able 
to exist after the resuscitation of life, will probably, for some time, 
defy the attempts of even the most careful and conscientious experi- 
mentalists to define satisfactorily under what circumstances the lowest 
known types first spring into existence. 
But we must now take our departure from the field of natural his- 
tory, and return once more to the consideration of those topics which 
