An Introduction to General Biology (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1895 Excerpt: ... entering into a loose association with complex organic substances in the protoplasm, and then suddenly combining with them under the appropriate stimulus to form simpler and more highly-oxidized products. Of the precise nature of the process we are quite ignorant. Outgo. Just as the income of the animal represents only the first term in a series of constructive processes, so the outgo is the last term of a series of destructive actions of which we really know very little save through their results. The outgo is shown in the accompanying table. Both energy and matter leave the cells, and finally leave the body--the former as heat, work done, or energy still potential (in urea and other organic matters); the latter as excretions, which diffuse freely outwards through the skin and nephridial surfaces. Of the daily outgo the water, carbon dioxide, and salts are devoid of energy, but the urea contains a small amount which is a sheer loss to the animal. Were the earthworm a perfect machine it could use this residue of energy by decomposing the urea into simpler compounds viz., ammonia (NH, ), carbon dioxide (CO, ), and water (H2O); but it lacks this power, though there are certain organisms (Bacteria) which are able to utilize the last traces of energy in urea (p. 107). To the daily outgo must be added the occasional loss both of matter and of energy suffered in giving rise to ova and spermatozoa, and in providing a certain amount of food and protection for the next generation. Interaction of the Animal and the Environment. The action of the environment upon the animal has already been sufficiently stated (p. 97). It remains to point out the changes worked by the animal on the environment. These changes are of two kinds, mechanical (or physical) and chemical. The .