MORPHOLOGY OF THE BLOOD 



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day as being sufficiently accurate for ordinary purposes. It has been also 

 shown that there are many distinct physiological variations in the number, 

 depending on the time of day, digestion, sex, etc. The number of red cells 

 usually diminishes in the course of each day, while the leucocytes increase 

 in number. It has been suggested that this is due to the influence of 

 digestion and of exercise. 



It has generally been found that within half an hour or an hour after a 

 full meal the number of red cells begins to diminish, and that this keeps up 

 for from two to four hours, when it is followed by a gradual rise to the normal. 

 The usual fall is 250,000 to 750,000 per cubic millimeter. These results 

 are most marked after a largely fluid meal, and are probably due to dilution 

 of the blood as a result of the absorption of fluids. In animals the number 

 of red cells is increased by fasting, but in man the results are variable, some 



FIG. 109. 



FIG. no. 

 The rounded or uncolored corpuscles are 



FIG. 109. Red Corpuscles in Rouleaux, 

 leucocytes. 



FIG. no. Corpuscles of the Frog. The central mass consists of nucleated colored 

 corpuscles. The other corpuscles are two varieties of the colorless form. 



authorities claiming an increase and others a decrease. In childhood there 

 is no difference between the sexes in the number of red cells per cubic milli- 

 meter, but after menstruation is established a relative anemia develops in 

 women. Welcker's original estimate placed the difference at 500,000 per 

 cubic millimeter, and these figures have been generally accepted, though 

 Leichtenstein asserts that the difference is 1,000,000. 



Menstruation in healthy subjects has practically no effect, as not more 

 than 100-200 cubic centimeters of blood are lost normally in the course of 

 several days. Under such circumstances the normal diminution of red cells 

 per cubic millimeter is probably less than 150,000, though Sfameni has placed 

 the loss at about 225,000. The leucocytes are slightly increased during 

 menstruation. It is now the general opinion that pregnancy has little or no 

 effect on the number of red cells, and that any anemia must be due to abnormal 

 conditions. Post-partum anemia should not last longer than two weeks. 



