I S§ 5 -j The Distinction between Animals and Ve 
getables. 275 
IV. THE DISTINCTION BETWEEN ANIMALS 
AND VEGETABLES. 
,r Z S , Comtean classification of the sciences, 
we find it laid down that each member of the hierarchy 
for h t',?. - dePend ‘" g f ? r ‘ ts methods . and sometimes even 
101 its doCtnnes upon those preceding it, is independent nf 
those which succeed it. Thus, according to ihfs view“V 
chemistiy is dependent upon physics and astronomy, but has 
nothing to learn from biology or from sociology. Physics is in 
like manner assumed to involve astronomy '(and, of course 
mathematics), but to have no need of chemistry and biology! 
1 hat this classification, like every other mere linear arran^e- 
ment of things classifiable, has failed to give satisfaction to The 
careful inquirer is a fact open and palpable. But two instances 
ot its departure from the truth are so striking, and at the 
same time so important in their teachings and in their results 
that we must give up a few minutes to their special 
consideration. y 
The older and better known of these instances is at once 
suggested by the mere mention of the spectroscope. Here 
is an instrument which can be rightly understood and used 
only by persons conversant with physics and with chemistry. 
Yet this instrument is now recognised as one of the ordinary 
working tools of the astronomer. By its aid he studies not 
merely the temperature and the composition of the heavenly 
bodies, but even obtains information as to their movements. 
He is thus compelled to be a physicist and a chemist if he is 
to use the instrument aright. 
Our second instance has come under public consideration 
more recently, and still presents unexplained phases not a 
few. We need merely mention the name of Pasteur to 
remind our readers that a number of important chemical 
decompositions and other changes which a little while a^o 
were classified as “ catalytic ” are now traced to the adtion 
of “ figured ferments.” These ferments are living beings re- 
producing their like by spores or germs and “ breeding true” as 
decidedly as does an oak or a whale. Their vital activity is 
not merely found indispensable in the conversion of sugars 
into alcohol, vinegar, &c. They are required to break* up 
dead animal and vegetable matter into simpler compounds 
but even such processes as nitrification are now shown to 
depend on the presence of these microbia. Hence we can 
