y related in function and together they form the nutrient fluid referred to in the preceding chapter. T

de to circulate through all parts of the body, but from them it does not escape under normal conditions. Though provisions exist whereby liquid materials ma

avier and denser than water; to have a faint odor and a slightly salty taste; to have a bright red color when it contains oxygen and a dark red color when oxygen is absent; and to und

d blood. B. Arrangement of red corpuscles in rows between which are white corpuscles,

ne of these is a clear, transparent liquid; while the other is made up of many small, round bodies that float in the liquid. The liquid portion of the blood is called the plasma; the small bodies are known as corpuscles. Two var

stance having a red color, known as hemoglobin. The shape of the red corpuscle is that of a circular disk with concave sides. It has a width of about 1/3200 of an inch (7.9 microns7) and a thickness of[pg 026] about 1/13000 of an inch (1.9

se from mammals are without nuclei, while those

cells. They take up oxygen at the lungs and release it at the cells in the di

is due the colors of the blood. When united with the oxygen it forms a compound, called oxyhemoglobin, which has a bright red color; the hemoglobin alone has a dark red color. These colors are the same as those of the blood as it takes on and gives off oxygen. The stroma, whi

hs, all the red corpuscles in the body at a given time will have disappeared and their places taken by new ones. The origin of new corpuscles, however, and the manner of ridding the

XIV) and consists, to a large extent, of cells somewhat like the red corpuscles, but differing from them in having nuclei. These appear to be constantly in a state of reproduction. The blood, flowing through the minute cavities contain

ey are much less numerous than the red, there being on the average only one white [pg 028]corpuscle to about every five hundred of the red

onditions are normal, but at B some excitation in the surrounding tissue leads

e walls of capillaries and to pass with the lymph in between the cells of the tissues. The white corpuscles are, therefore, not confined to the blood vessels, as are the red corpuscles, but migrate through the i

the body, but usually takes place in the lymphatic glands (Chapter VI) and in the spleen, where conditions for their dev

s destroying germs that may be present in the blood, the white corpuscles also leave the blood and attack germs that have invaded the cells. By forming a kind of wall around any foreign substance, such as a splinter, that has penetrated the skin, they are able to prevent the spread of germs through the body. In a

nd of substances dissolved in the water. The dissolved substance

. These resemble, in a general way, the white of raw egg, but differ from each other in the readiness with which they coagulate. Fibrinogen coagulates more readily than the others and is the only one that changes in the ordinary coagulation of the blood.

plasma is in minute quantities and appears as fine droplets-the form in which it is found in milk. While several mineral salts are present in small quantities in the plasma, sodium

od plasma. They are carried by the blood until removed by the organs of excretion. The

mount. The remaining 90 per cent is water. Practically all the constituents

stituents of the plasma and floating the corpuscles. Deprived of its water, the blood becomes a solid substance. Through the movements of the blood the water also serves the purpose of a transporting agent in the body

culiar change known as coagulation.11 In this change the corpuscles are collected into a solid mass, known as the clot, thereby separating from a liqui

alled the coagulable constituent of the blood. In the plasma the fibrinogen is in a liquid form; but during coagulation it changes into a white, stringy solid, called fibrin. This appears in the clot and is the cause of its formation. Forming as a network of [pg 032]exceedingly fine and very delicate thread

r). These by contracting draw the co

nt is as follows: Fibrinogen does not of itself change into fibrin, but is made to undergo this change by the presence of another substance, called fibrin ferment. This substance is not a regular constituent of the blood, but is formed as occasion requires.

from the blood, coagulation does not take place. These are, however, regular constituents of healthy blood. Whether the presen

connected vessels causes it to escape rapidly from the body whenever openings in these vessels are made. Clots form at such openings and close them up, stopping in this way the flow that would

s the process. It may be prevented entirely by lowering the temperature of the blood to near the freezing point. The presence of a foreign substance increases the rapidity of coagulation

l is an amount weighing nearly twelve pounds and having a volume of nearly one and one half gallons. About 46 per cent by volume of this amount i

the cells and waste materials from the cells. Much of the blood may, therefore, be regarded as freight in the process of transportation. The blood also carries, or distributes, h

034] this function is mainly due to the white corpuscles, it is due in part to the plasma.13 Through its coagulatio

mains constant although the water is continually

hanges most rapidly. Yet in spite of these changes the quantity and character of the blood remain practically constant.14 This is because there is a balancing of the forces that bring about the changes. The addition of various materials to the blood just equals the withdrawal

good, one[pg 035] should cultivate those habits that are beneficial and avoid those that are harmful in their effects. Most of the hygiene of the blood, ho

and avoid the use of injurious drugs. On the other hand, they are deficient in quantity and inferior in quality in the bodies of those who pursue an opposite course. Impurities not infrequently find their way into the blood through the digestive organs. One should eat wholesome,

ase. Many patent medicines are widely advertised for purifying the blood. While these may possibly do good in particular cases, the habit of doctoring one's self with them is open to serious objection. Instead of taking drugs and patent medicines for purifying the blood, o

carried. The latter, which include food and oxygen for the cells and wastes from the cells, may be classed as freight. Certain constituents in the blood destroy disease germs, and other constituents, by coagulating, close s

with reference to weight, density, col

e the different cons

uscles with reference to size, sh

purpose for each con

ay be regarded as freight and what

of the blood are found in the clot?

are served by w

tly changing, is kept about the same

bright red color and in the tissues it changes ba

ng instead of a weak chemical union, could the

living favor the developmen

in clean and active improve

TICA

antity in the following experiments, it is best obtained from the butcher. To be sure of securing th

is cooling, stir rapidly with the hand o

l and set aside witho

nd thoroughly mix with t

fifth full of a saturated solution of Epsom salts. The purpose of the salts is to prev

rface of water in a glass vessel. Does it remain on the surface or sink to the bottom?

er. Then place the hand over the mouth and shake until the blood is thoroughly mixed with the air. Compare with a portion of the b

bler in the[pg 038] same manner, and after another half hour add blood to the third. The water dilutes the salts so that coagulation is no longer prevented. Jar the vessel occasionally as coagulation proceeds; and if the clot is slow in forming, add a trace of some salt

large vessel of water. Thoroughly wash, adding fresh water,

entral mass (the clot) surrounded by a clear liquid (the serum). Sketch the vessel and i

ing. (To prevent any possibility of blood poisoning the needle should be sterilized. This may be done by dipping it in alcohol or by holding it for an instant in a hot flame. It is well also to wash the finger with soap and water, or with alcohol, before the operation.) Place a small drop of the blood in the middle of a glass slide, protect the same with a cover glass, and examine with a compound microscop

become separated by the formation[pg 039] of the red corpuscles into rows. They are easily recog

e fingers to squeeze out a whitish, semi-liquid substance. Dilute with physiological salt solution on a glass slide and

crayon. Excellent models can be molded from plaster of Paris as follows: Coat the inside of the lid of a baking powder can with oil or vaseline and fill it even full of a thick mixture of plaster of Paris and water. After the plaster has set, r

g