THEORIES OF COAGULATION. 171 
digesting these with calcium chloride, the excess of calcium salt being 
afterwards dialysed off. Pekelharing supposes thai the ferment action 
consists in the transference of lime from its nucleo-proteid combination 
to fibrinogen, the lime-compound of this being the insoluble fibrin, 1 and 
that if there is more lime salt in the solution the nucleo-proteid can 
recombine with lime, and thus become reconstituted as an agent for the 
conversion of fibrinogen into fibrin. As already pointed out (p. 166), 
however, it is not possible to arrest this theory in view of the analyses 
of fibrin and fibrinogen given by Eammarsten Pekelharing has himself 
shown that even in the entire absence of free lime salts, or in the 
presence of soluble oxalates, the transformation of fibrinogen into fibrin 
may be produced, provided that the ferment is present. 2 This has also 
been shown to be the case by A. Schmidt 3 and by myself, 4 and more 
recently in a series of carefully conducted experiments by Hammarsten. 
Hammarsten precipitated fibrinogen by oxalated solution of salt, and, 
after purifying it by repeated re-solution and re-precipitation, added to 
its solution a fibrin ferment obtained from oxalated serum, and obtained 
as the result a typical fibrin. 5 
Exception has been taken to the inference drawn by Pekelharing that 
Schmidt's ferment is a compound of nucleo-proteid and lime, on the ground 
that the ferment contained in Schmidt's extract differs from nucleo-proteids 
in the effect of alcohol upon its solubility in water, and in the fact that 
nucleo-proteids cause coagulation in intravascular plasma, which Schmidt's 
extract does not, whereas the latter causes coagulation in extravascular (salted) 
plasma, and nucleo-proteids do not. 6 The differences may, however, depend, 
in part at least, upon the relative amounts of nucleo-proteid and lime. Thus 
in Schmidt's extract the amount of nucleo-proteid is small and the amount of 
lime large ; in extracts of thymus and the like the amount of nucleo-proteid 
is large and the amount of lime small. In part also they depend upon other 
circumstances, such as the influence of the magnesium sulphate of the salted 
plasma in antagonising the effect of lime." 
The origin of the nucleo-proteid of plasma and serum is probably the white 
corpuscles. It would appear that many of the latter disintegrate after removal 
of blood from the body. Giirber 8 found that in coagulated blood the number 
of white corpuscles was reduced to one-half, the difference being chiefly in the 
number of polynuclear cells. This disappearance has not, however, been 
found by all observers, and is not fully admitted. Nevertheless, without 
actually disintegrating, the white corpuscles may shed out or secrete nucleo- 
proteid into the plasma. This may occur normally in mere traces, but on with- 
1 Centralbl. f. Physiol., Leipzig u. Wien, 1895, No. 3. 
2 It would appear that a soluble oxalate does not throw down all the lime from a proteid- 
containing fluid, and that a trace of lime is still held in solution so that an oxalate plasma 
is not lime-free, as was supposed by Arthus and Pages. This is well illustrated by an 
observation by Ringer upon the frog's heart, who finds that a normal saline solution, 
to which a little CaCl 2 has been added, will exhibit the physiological effect of lime, 
even after the addition to the fluid of a slight excess of a soluble oxalate. It may be 
inferred from this that a trace of lime may be held in solution even in a fluid destitute of 
proteid. 
3 "Weitere Beitr. ?.. Blutlehre," Wiesbaden, 1895. 
4 Proc. Physiol. Soc, Journ. Physiol., Cambridge and London, 1895, vol. xvii. 
p. xviii. 
5 Ztschr. f. physiol. Chem., Strassburg, Bd. xxii. 
6 Halliburton and Brodie. Journ. Physiol., Cambridge and London, 1891, vol. xvii. p. 113. 
7 Pekelharing, Centralbl. f. Physiol.", Leipzig u. Wien. 1895, Bd. ix. S. 102. Halliburton 
in a recent paper {Journ. Physiol., Cambridge and London, 1895, voL xviii.) comes to a 
similar conclusion, namely, that Schmidt's fibrin ferment is a weak solution of nucleo- 
proteid. It produces Wooldridge's negative phase when intravenously injected. 
8 Sitzungsb. d. phys. -tried. Gesellsch. zu Wiirzburg, 1S92, No. 6. 
