Popular Books on Natural Science

in the human body, we must first obtain a

we oblig

lso, that above all we must ask, whence hunger arises; that we must first

of you it is a well-known fact, that nothing in the human body remains even for a moment in the same state; but that in every part of the body a continued exchange takes place. Air is breathed in

formed parts of it, and is therefore obliged, in order to compensate for the loss, to take in new matter. Hence there is no exaggeration in the expression, "Man is continually renewing himself;" we indeed lose and receive particles o

nvoluntarily and suffers so many losses-by the mere process of breathing he ejects matter which he must replace afterwards-this exchange of matter is the cause of the body's poss

f continual losses. It is the wonderful transformatio

at have eaten food; but rather that they themselves, viz., their skin, hair, bones, brain,