Page:The American Cyclopædia (1879) Volume II.djvu/751

 BLOOD 731 corpuscles of the most remarkable size. The measurements are all made in vulgar fractions of an English inch.; but for the sake of conve- nience, the numerator, being invariably 1, is omitted, and the denominators only are printed. These measures show that the size of the blood corpuscles is not at all in proportion with the size of the animal. For instance, the corpus- cles of man are larger than those of the ass, the horse, the bear, the lion, the tiger, &c., which are larger animals than man. It is nevertheless remarkable that the elephant and the whale are among the animals whose blood corpuscles are the largest. In the same individual the blood disks are not all of the same size; in man their diameter varies between j^Vs to j-j-Vs of an mcn ) the average being s-jVj. The red corpuscles of man, although larger than those of most of the mammalia, are so small (the oW P ar t f an inch) that, according to Home, 19,880 of these corpuscles, placed side by side, would cover only a surface of a square inch. Young says that to cover such a surface 255,000 corpuscles would be necessary. The number of red corpuscles in the body of a man is immense. To convey an idea of this num- ber, we will merely state that, according to StOltzing, there are from three to four or five millions of corpuscles in one cubic millimetre (the linear millimetre being about ^ of an inch). Vierordt and Voelcker had already ob- tained analogous results. The red corpuscles are very elastic and pliant, so much so that they may pass through blood vessels the diame- ter of which is somewhat smaller than theirs. They exist in all the vertebrata except one, the lancelet (amphioxus lanceolatus), a very singu- lar and little developed fish. 2. White or color- lens corpuscles. These globules seem to have been seen for the first time by the celebrated Hewson, in the last century. However, it is only in our days that they have been well stu- died. They are found in all the vertebrata, in- cluding the amphibia, whose blood has no other corpuscle. They are much more globular than the red corpuscles, but not perfectly spherical; they have a granular capsule and a nucleus of several small ones. They are quite pale or colorless; they do not contain iron, and have much more fat than the red corpuscles. Their size hardly varies in the different classes of ani- mals, so that they are in some smaller and in others larger than the red corpuscles, which vary much in size. In warm-blooded animals (man included) they average rather more than infof f an mcn m diameter. An interesting fact concerning the pale corpuscles of the blood is, that they seem to be endowed with the faculty of altering their form. According to the discovery of Mr. Wharton Jones, and to the more recent researches of M. Davaine, they often show a slow protrusion from their membranous wall; after which another one forms itself in another part, while the first slowly disappears; sometimes a depression is formed instead of a protrusion. These changes have been seen even in circulating blood in living animals. These spontaneous alterations of form have been considered by some phys- iologists as a proof that these cells or cor- puscles are microscopical animals. But ap- parently spontaneous movements are not suf- ficient signs of independent life, for, admitting that these corpuscles are animalcules, Brown- Sequard has shown that all the muscles of man or of animals, separated from the body, may have apparently spontaneous movements; so that we should have to admit that each elementary muscular fibre is a distinct animal being, if apparently spontaneous motions were a proof of the existence of an independent liv- ing organism. The number of colorless cells is very much smaller than that of the red disks. There is one colorless corpuscle to 300 or 400 red, according to Bonders and Moleschott. The number of colorless cells increases more than that of the red disks after eating, and par- ticularly after taking albuminous food. 3. Mo- lecular elements. There is in the Wood a number of exceedingly small solid particles which the French (Donne, Robin) call globulins (small globules). Their nature is unknown, and their form has no definite character; it may be that they are particles of coagulated fibrine. 4. Pigment. There is frequently, and perhaps always, in the blood of man and of the higher animals, a small quantity of black pigment un- der various forms. Sometimes there are only exceedingly fine granules, like those of the skin (which are the cause of its color); in other cases there are plates of pigment, which seem chiefly to result from an aggregation of granules. The presence of cells containing black pigment is very rare in the blood. From the researches of Brown-Sequard, it seems that the quantity of pigment increases in the blood of animals when the supra-renal capsules have been extirpated. The accumulation of pig- ment in the blood of man, according to Planer, and in that of animals, according to Brown- Sequard, is a cause of rapid death. 5. Crys- tals. It happens, though very rarely, that without any preparation the blood corpuscles become decomposed, and their coloring matter, slightly changed in its chemical composition, forms rhomboidal or simple needle-shaped crys- tals. By the addition of water, of ammonia, or some other reagents, it is easy to produce many crystals in a drop of almost any blood, as has been ascertained by Virchow, Kunde, O. Funke, Reichmann, and others. M. Charles Robin has once found in the liver a mass of altered blood as large as a hazel nut, entirely transformed into crystals, or rather containing nothing but haama- tine crystallized, the other elements of the blood having been absorbed. Brown-Sequard has pointed out the fact that, in dogs especially, after the extirpation of the supra-renal capsules, the formation of crystals in the blood is very considerable and rapid. 6. Coagulated fibrine. Some micrographers, especially Nasse and Vir- chow, call certain solid particles floating in the