CHEMICAL CONSTITUENTS :-ALBUMEN. 
31 
Chemical Constitution of the Animal Body. 
13. Ey far tlie larger proportion of tire Animal fabric is 
formed at the expense of the substance termed A lbumen ; the 
composition and properties of which, therefore, claim onr 
first attention. The fundamental importance of albumen in 
the animal economy, is shown by the fact that it constitutes, 
with fat, and a small proportion of certain mineral ingredients, 
the whole of that mass of nutrient material stored up in the eggs 
of oviparous animals, which, being appropriated by the germ 
to the building up of its fabric, is converted by it into the 
bones, muscles, nerves, tendons, ligaments, glands, mem¬ 
branes, &c. of the embryo. We find it also constituting a 
large proportion of the solid matter of the blood and other 
nutrient fluids of the adult animal; and it is the fundamental 
form to which the various azotized substances employed as 
food (§ 153)—such as animal flesh, or the gluten of bread— 
are first reduced by the act of digestion. It is composed 
of 49 carbon, 36 hydrogen, 14 oxygen, 6 nitrogen, with a 
minute proportion of sulphur ; it is generally blended, also, 
with more or less of fatty matter, and with saline and earthy 
substances. 
14. Albumen may exist in two states,—the soluble and 
insoluble. In the animal fluids it exists in its soluble 
form; and is united (as an acid to its base) with about 1^ 
per cent, of soda, forming an albuminate of soda. It is not 
altered by being dried at a low temperature, but still retains 
its power of being completely dissolved in water. When a 
considerable quantity of it exists in a fluid (as in the white of 
the egg), it gives to it a glairy tenacious character; but it is 
nearly tasteless. When such a fluid is exposed to a tempe¬ 
rature of about 150°, a coagulation or ‘setting’ takes place, as 
in the familiar process of boiling an egg. Eut if the albumen 
be present in smaller quantity, the fluid does not form a 
consistent mass, but only becomes turbid; and this only after 
being boiled. Albumen which has been dried at a low 
temperature, however, may be heated to the boiling point of 
water, without passing into the insoluble condition ; a fact 
which is of peculiar interest in relation to the power which 
the Tardigrada (Zool. § 841) possess, of sustaining a very 
high temperature without the loss of their vitality, when 
