PATHOLOGICAL METABOLISM OF THE BLOOD 557 



green) a blue-staining reticulum is demonstrable in a very small per- 

 centage of normal red blood-cells; the normal figure for adults being 

 one-half to two per cent. In pathological conditions calling for increased 

 bone-marrow activity, reticulated cells have been found considerably in- 

 creased. The percentage may vary from one to four per cent in anemias, 

 and in cases of hemolytic jaundice they may reach the very high figure of 

 fifteen to twenty per cent. Whether the reticula are nuclear fragments of 

 immature erythrocytes or the results of a disease process is not yet defi- 

 nitely established. Their identification, however, is of the greatest diag- 

 nostic value, and their diminution or disappearance as the result of 

 treatment may be taken as a sign of good prognostic significance. 



A determination of the number of blood-platelets by the newer methods 

 (Wright and Kinnicutt, Gram) also yields information of value concern- 

 ing the activity of the marrow in blood formation. The value of platelet 

 counts in this connection is based on the observation that their number 

 is reduced in conditions with defective regeneration and that they may 

 be increased after splenectomy in pernicious anemia (Lee). In diseased 

 conditions a gradual change of these elements of the blood in the direction 

 of normal figures may therefore be taken as a sign of improvement. 



The estimation of the number of erythrocytes containing mitochondria 

 may also prove to be a useful indication of the rate of red blood-cell 

 formation (Sappington). Mitochondria are small bodies of a lipoid na- 

 ture which occur in the cell protoplasm, and which may be stained in 

 a specific manner. They are not demonstrable in the circulating ery- 

 throcytes of healthy adult mammals, but are regularly present in nu- 

 cleated red blood-cells. Their occurrence in non-nucleated cells is there- 

 fore supposed to indicate that such erythrocytes are relatively imma- 

 ture. 



The methods so far considered are for the most part qualitative. A 

 more quantitative measure of the rate of blood regeneration may come 

 from the recent work on the oxygen consumption of the formed elements 

 of the blood, and more especially of the red blood-cells. It has been 

 shown by Morawitz(a) and his co-workers that normal human blood con- 

 sumed" very little oxygen, whereas the oxygen absorption of the blood 

 of patients suffering from the various types of anemia may be marked. 

 Furthermore, it appears that this increased absorption is due to the 

 young, unnucleated cells and not to the erythroblasts of the blood. 

 Harrop(fe) has recently confirmed these findings. He has also made the 

 interesting observation that the oxygen consumption of the blood in 

 various types of anemia is proportional to the percentage of reticulated 

 cells present. The demonstration of increased oxygen absorption by pres- 

 ent-day methods may therefore prove to be a more accurate quantitative 

 index of functional variations in bon&marrow activity than microscopic 

 evidence alone. 



