150 THE BLOOD. 
blood-counting apparatus (hemacytometer) of Gowers and of Thoma. 1 
The hematocrit 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 
clue, 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 Archvo, 1882, Bd. lxxxvii. 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, seance du 31 Oct. 1874, Gaz. 
mid. 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, dc physiol. 
norm, etpath., Paris, 1874, et scq. 
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. 
"Grawitz, Berl. Hin. Wchnschr., 1895, S. 713 and 740. Of. also A. Fick, Arch. f. d. 
ges. Physiol.. Bonn, 1895, Bd. Ix. S. 589. Grawitz points out that at altitudes below 
16,000 leet 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 
