142 MINUTE ORGANISMS. 
It is evident that the chemical, and in many cases the 
mechanical, character of a great number of the objects impor- 
tant in the material economy of human life, must be affected 
by the presence of so large an organic element in their sub- 
stance, and it is equally obvious that all agricultural and all 
industrial operations tend to disturb the natural arrangements 
of this element, to increase or to diminish the special adaptation 
of every medium in which it lives to the particular orders of 
being inhabited by it. The conversion of woodland into pas- 
turage, of pasture into plough land, of swamp or of shallow sea 
into dry ground, the rotations of cultivated crops, must prove 
fatal to millions of living things upon every rood of surface 
thus deranged by man, and must, at the same time, more or 
less fully compensate this destruction of life by promoting the 
growth and multiplication of other tribes equally minute in 
dimensions. 
I do not know that man has yet endeavored to avail himself, 
by artificial contrivances, of the agency of these wonderful 
architects and manufacturers. We are hardly well enough ac- 
quainted with their natural economy to devise means to turn 
their industry to profitable account, and they are in very many 
cases too slow in producing visible results for an age so impatient 
as ours. The over-civilization of the nineteenth century cannot 
wait for wealth to be amassed by infinitesimal gains, and we 
are in haste to speculate upon the powers of nature, as we do 
upon objects of bargain and sale in our trafficking one with an- 
other. But there are still some cases where the little we know 
of a life, whose workings are invisible to the naked eye, sug- 
gests the possibility of advantageously directing the efforts of 
on the now exploded supposition that all of them are animated, which was the 
general belief of naturalists when attention was first drawn to them. It was 
soon discovered that many of them were unquestionably vegetable, and there 
are numerous genera the true classification of which is matter of dispute among 
the ablest observers. There are cases in which objects formerly taken for liv- 
ing animalcules turn out to be products of the decomposition of matter once 
animated, and it is admitted that neither spontaneous motion nor even appa- 
rent irritability are sure signs of animal life. 
