ISO THE BLOOD. 



blood-counting apparatus (haemacytometer) of Gowers and of Thoma. 1 

 The hsematocrit can also be employed, since it has been determined (by 

 exact enumeration.) that each volume per cent, shown by that instrument 

 represents 97,000 corpuscles. A still readier mode of rapidly estimat- 

 ing the number of red corpuscles in a sample of blood is that of G. 

 Oliver. 2 Oliver takes a small measured quantity of blood and mixes it 

 in a graduated glass tube with Hayem's fluid, 3 until the flame of a candle 

 placed at a certain distance behind becomes apparent through the mix- 

 ture. With 5,000,000 corpuscles per cent, the mixture will now be 

 found to fill the tube to a certain point. This point is taken as the 

 normal (or 100 per cent.), and above or below it the tube is graduated 

 in percentages. The fine flutings which are produced in drawing out 

 the tube enable the point at which the flame first becomes visible to be 

 determined with great accuracy, for they cause it to appear as a trans- 

 verse luminous line, and it is in this factor that Oliver's application of the 

 method is superior to previous attempts that have been made to apply it. 

 The following results have been obtained by Oliver and others : 

 There is a diurnal variation in the percentage of corpuscles, which 

 falls somewhat during the daytime and rises at night. This variation 

 amounts to between 4 and 5 per cent, of the normal number. Food 

 usually produces a fall in the number of red corpuscles, independent of 

 the amount of water taken with the meals. The posture of a limb has 

 a considerable influence on the number of corpuscles obtained from it 

 by a prick, probably in keeping with alterations in the intracapillary 

 pressure, which governs the production of lymph. Muscular exercise, 

 whether active or passive (voluntary movements, electrical stimulation, 

 massage, passive movement of limbs), causes an increase in the per- 

 centage of the corpuscles, which is sometimes very marked. 4 This may 

 also be due to a difference in the production and flow of lymph in 

 the part. The number is increased in the case of residents in high 

 altitudes (to as much as 8,000,000 ! per c.mm.). 5 This appears to be 

 due, partly to increased evaporation from the general surface, and loss 

 of water from the blood; partly to increased arterial tension, which 

 increases the amount of lymph formed ; probably not to increased 

 formation of red corpuscles. 6 It is also increased in certain diseased 

 conditions (e.g. gout), but more commonly it is diminished in disease. 



1 Lancet, London, 1877, vol. ii. p. 797 ; Virchow's Archiv, 1882, Bd. Ixxxvii. S. 201. The 

 older literature is given by Rollett in Hermann's "Handbuch," 1880, Bd. iv. Th. 1, S. 27-31. 



2 G. Oliver, Croonian Lectures, Lancet, London, 1896, vol. i. 



3 Distilled water, 200 c.c. ; sulphate soda, 5 grms. ; common salt, 1 grm. ; corrosive 

 sublimate, 0'5 grm. See Hayem ("Du Sang," Paris, 1889), where will be found an 

 extended series of observations upon the microscopical characters of the blood. 



4 Noted also by Malassez, Compt. rend. Soc. d. bioL, Paris, stance du 31 Oct. 1874, Gaz. 

 med. de Paris, 1874, p. 573. For numerous other observations by this author consult "De 

 la numeration des globules rouges du sang," Paris, 1873, and papers in Arch, de physiol. 

 norm, etpath., Paris, 1874, et seq. 



5 Viault, Compt. rend. Acad. d. sc., Paris, 1890, tome cxi. p. 917 ; and 1891, tome cxii. 

 p. 295. Oliver (Croonian Lectures. Lancet, London, 1896, vol. i. p. 1782) gives a useful 

 epitome of what is known at present on this subject, together with many original observa- 

 tions. 



6 Grawitz, Berl. Jclin. Wchnschr., 1895, S. 713 and 740. Cf. also A. Fick, Arch. f. d. 

 ges. Physiol., Bonn, 1895, Bd. Ix. S. 589. Grawitz points out that at altitudes below 

 16,000 feet there is no need for a compensatory increase in number of red corpuscles, since 

 the experiments of Frankel and Geppert have shown that in dogs subjected to an atmo- 

 spheric pressure, equal to that at this altitude, there is just as much oxygen taken up by 

 the blood as at the ordinary pressure. Miintz found relatively more iron in the blood 

 of rabbits and sheep from near the top of the Pic du Midi than in others living in the 



