102 ON THE ELEMENTARY PARTS OF THE HUMAN FABRIC. 



2. On the Original Components of the Animal Fabric. 



111. Putting aside, for the present, the inorganic or mineral matters which 

 enter into the composition of the Animal body, and which are left in the form 

 of an ash, when the organic compounds are decomposed and dissipated by 

 heat, we shall confine our attention to the peculiar characters of the latter. 

 As already stated ( 4), the organized tissues of Plants are found, when en- 

 tirely freed from the contents of their cells, to have a very uniform composi- 

 tion; being entirely made up of Carbon united with the elements of Water in 

 a very simple proportion, that of 8 of the former to 7 of each of the latter; 

 and this simplicity in their chemical character partly accounts for their com- 

 parative durability. There are various compounds found in the cells of Plants, 

 and elaborated by them for the purpose of affording food to Animals, which 

 do not undergo organization, so long as they are contained in the Vegetable 

 fabric; but these very products, when transferred to the bodies of Animals, 

 form the components of their solid tissues. These substances are distinguished 

 by the presence of Azote or Nitrogen, in considerable amount; and also by the 

 large number of atoms of the four components, which are united in each of 

 them, giving them a much more complex composition, and a much greater 

 tendency to decay, this being brought about by the disposition of the compo- 

 nents to enter into new compounds of a simpler and more permanent nature. 

 A considerable variety of such substances exists in the different parts of the 

 Human body ; but the nature and composition of these may be better studied, 

 when their structure and actions are being described; and at present we shall 

 confine ourselves to the fundamental or original components, of which all the 

 others may be regarded as modifications. 



112. When we examine the Egg of an Oviparous animal, we find that, 

 putting aside the fatty matter of the yolk (which is destined, not to be con- 

 verted into tissue, but to be stored up in cells), the sole organic constituent is 

 that which is known to Chemists as Mbumen. By the wonderful processes 

 of chemical and vital transformation, which take place during the period of 

 incubation, and which are effected by the germ-cell and its descendants, this 

 Albumen is metamorphosed into nerve, muscle, tendon, ligament, membrane, 

 areolar tissue, horny substance, feathers, the organic basis of bone, &c. The 

 same metamorphosis is continually taking place in the adult animal; for every 

 substance of similar composition, that is employed as food, is reduced to the 

 form of Albumen in the digestive process; so that this becomes the essential 

 constituent of whatever fluid is absorbed for the nutrition of the tissues. It 

 is true that Gelatine, taken in as food, may be absorbed and carried into the 

 current of the circulation ; but there is little doubt, that it is incapable of 

 being applied to the reconstruction of any but the gelatinous tissues ; and in 

 these it exists in the very lowest form of organization, if organization it can 

 be called. Moreover, as it is clear, from what has been just stated, that the 

 gelatinous tissues may be formed at the expense of Albumen, we are justified 

 in regarding the latter substance as the common pabulum for all. Hence Albu- 

 men seems to hold very much the same position in the Animal economy, witli 

 Gum in the Vegetable. 



113. The properties of Albumen may be studied in the White of Egg, or 

 in the Serum of Blood ; from both of which situations it may be obtained in 

 a pure state by very simple means. In the Animal Fluids it exists in a so- 

 luble state; and even when it has been dried (at a temperature of 126), it 

 is readily dissolved again in water, forming a glairy, colourless, and nearly 

 tasteless fluid. In this condition it is always combined with a small quan- 

 tity of free soda; to the separation of which (whether by the agency of heat 

 or acids), its coagulation is thought by many Chemists to be due. On this 



