BLOOD. 481 



Albuminoids of various sorts form the great mass of the white 

 blood-corpuscles. These correspond mainly to the albuminoids which 

 are found in the blood-plasma, which, together with the paraglobulin , 

 or fibrino-plastic substance, will be described in the consideration of the 

 coagulation of the blood. 



The protoplasm of the colorless blood-cells undergoes partial coagu- 

 lation at 40° C. It swells and becomes transparent when treated with 

 acetic acid, the nuclei becoming more distinct. With 10 per cent, salt 

 solution the protoplasm swells and becomes dissolved (leaving the nuclei 

 intact) , the solution being coagulable with heat and the mineral acids 

 and precipitated by dilution with water. The proteid constituents of 

 the white blood-cells are thus largely of a globulin-like nature. 



Of the carbohydrates, glycogen occupies the first rank in importance. 

 When treated with a solution of iodine (one gramme) in iodide of potas- 

 sium (two grammes in one hundred c.c. water) many of the white blood- 

 cells assume a reddish, mahogany color, while in others the body of the 

 cell stains deep yellow, numerous granules taking on the mahogany 

 tint which is characteristic of glycogen. From the importance which 

 glycogen has been found to possess for muscular contraction, it may be 

 assumed that the contractility of the white blood-corpuscles is developed 

 at the expense of the glycogen. 



Variable amounts of fat are also found in the protoplasm of the 

 white blood-corpuscles in the form of highly refractive granules. The 

 importance of this fat for the life processes of the blood-cells is as yet 

 undetermined. Whether it is formed as a result of the breaking down 

 of the cell-protoplasm, or whether it exists as a result of absorption 

 processes, is not certain, though the following experiment seems to 

 indicate the former origin. 



If a piece of dry pith is inserted into the abdominal cavity of a liv- 

 ing animal, the pores of the pith are soon found to be filled with blood- 

 serum and white blood-cells ; the latter pass into the interior of the pith, 

 and if, after remaining in the abdominal cavity for twenty-four hours, 

 the pith is examined under the microscope, the external layers will be 

 found to be occupied by perfectly normal, living, white blood-cells, while 

 those which are found in the central portions have assumed a spherical 

 form and undergone such extensive fatty degeneration that the pith 

 seems to be impregnated with fat-globules. 



Lecithin. — A phosphorized bod}' which has already been described 

 as a constituent of nearly all developing cells is also found as a constant 

 constituent of the white blood-cells. As regards the origin of this sub- 

 stance, there is also the greatest uncertainty, though there is some 

 evidence in favor of the view that it exists as a preliminary stage to 

 the formation of fat. Lecithin is capable of a high degree of aqueous 



31 



