THE BLOOD. 233 



above the blood always contains a number of other bodies of 

 more or less importance. Among these may be mentioned 

 the fats, soaps, cholesterol, lecithin and jecorin. The total 

 fats amount ordinarily to about 0.2 per cent, but after a meal 

 may be temporarily much increased. Minute traces of fatty 

 acids as soaps may be also present. Cholesterol appears to be 

 present in free form in traces and also as an acid combination 

 or ester. Lecithins are present in very small amount in both 

 corpuscles and plasma, but anything like a quantitative deter- 

 mination does not appear to be possible. The name jecorin 

 is applied to a peculiar substance containing phosphorus, de- 

 scribed by several observers. It is soluble in ether like lecithin 

 and seems to exist in combination with a carbohydrate group 

 or similar reducing residue. The substance has never been 

 obtained in form pure enough for analysis, and it is even pos- 

 sible that it may be a mixture of several compounds, one of 

 which is a combination of glucuronic acid. 



Variations in Disease. In disease the normal proportions of the various 

 substances may suffer marked changes. A decrease in the normal num- 

 ber of corpuscles (about 5 millions to the cubic millimeter for men, 4 to 

 4.5 millions for women) may follow to the extent of 10 per cent or more in 

 certain anemic conditions. There may also be a change in the proportion 

 of hemoglobin without a change in the number of corpuscles. The meth- 

 ods of estimating the amount of hemoglobin will be given later. The salts 

 in the blood suffer a percentage decrease after consumption of large quan- 

 tities of water, but only temporarily. An actual decrease may occur in 

 cholera and inflammatory diseases. The normal minute amount of sugar 

 is increased in diabetes, but not greatly, because of the eliminating power 

 of the kidneys. It may be temporarily increased by the use of certain 

 drugs such as curare, amyl nitrite, chloral, or by inhalation of chloroform 

 vapor. After meals rich in fats there is a temporary increase of fat in 

 the blood, but a persistent increase is noticed in the blood of drunkards 

 and of corpulent individuals. In diseases where there is a rapid breaking 

 down of proteins there is usually observed an increase of fat. 



A loss of blood to the extent of one-third is not necessarily dangerous 

 if it be withdrawn slowly. If one-half the blood is lost there is great 

 danger of death. Blood may be added by transfusion, but for safety should 

 be from an animal of the same species. The serum of one animal has usu- 

 ally a destructive action on the corpuscles of another. Transfused blood 

 then may be a source of danger rather than a means of saving life. This 

 peculiar action of serum will be referred to later in some detail. 



