177 



multiplied by 4000 times 100 to give the number of corpuscles in a 

 cubic millimeter of undiluted blood. 



THE H^EMATOCRIT. A rapid approximate determination of the 

 relative percentage of the corpuscles may be made by Daland's 

 instrument. The blood is sucked up the graduated tube without 

 dilution and then centrifuged. The corpuscles rapidly accumulate 

 at the end of the tube in an almost solid mass, and their collective 

 volume can be directly read off. The estimate can be made with a 

 small quantity of blood, and is, therefore, capable of being used for 

 clinical purposes. Daland found that 50 was normal; this, multi- 

 plied by 100,000, gives the number of corpuscles in 1 cubic milli- 

 meter. 



HAEMOLYSIS, OR LAKING OF BLOOD. 



Experiments Upon the Blood. Points of interest to the physiol- 

 ogist particularly and to the clinician incidentally have been dis- 

 closed as the results of some simple experimental work upon the 

 blood-corpuscles. Each red corpuscle is seen to be composed of a 

 fine meshwork, or stroma, consisting of noncolored, homogeneous 

 protoplasm. Scattered throughout this framework is the iron-hold- 

 ing pigment, which gives color to the corpuscle and is the substance 

 with which the oxygen-gas enters into loose combination. Any 

 reagent which is able to sever the union between stroma and 

 haemoglobin causes the latter to pass into solution in the plasma. 

 The once-red corpuscles then appear as transparent bodies. This 

 makes the blood dark red, but transparent, since the coloring mat- 

 ter is in solution. When the blood is in this condition it is said 

 to be "lake-colored." 



This discharge of the haemoglobin from the corpuscles is called 

 haemolysis. The substances which produce this state of affairs are 

 haemolytic agents. 



Overton holds that the surface layer of the protoplasm of all 

 animal and vegetable cells is impregnated with a layer of a compound 

 of cholesterin and lecithin which permits of a slow or rapid exchange 

 of substances between the cell and its medium. The static Osmotic- 

 features of a cell independent of its inherent protoplasmic activity 

 depends upon the solubility of substances in cholesterin-lecithin. 

 Hence the cell-envelope is permeable to most organic poisons, alka- 

 loids, phenol and antipyrin, whilst proteids or carbohydrates cannot 

 possibly enter the cell in a similar manner. The haemolytic action 

 of saponine, solanine and digitaline is regulated by the nature of 



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