1 7 6 THE BLOOD. 
of leucocytes to the circulating blood does not increase its coagulability, 
but the contrary; and, moreover, peptone plasma contains many 
leucocytes. 1 These several facts were explained by Wooldridge by 
the supposition that coagulation is produced or prevented in the 
absence of leucocytes by the action of one substance in the plasma upon 
another, or in the presence of leucocytes by the action of a substance 
within the plasma upon these cells, or material yielded by them ; the 
kind of interaction being different under different circumstances, and 
producing, respectively, the phase of incoagulability or coagulation 
(negative or positive phase) according to such circumstances. All such 
substances, which by their interaction tended to produce fibrin, were 
termed by Wooldridge " fibrinogens " ; but the progress of research has 
since rendered it probable that Wooldridge's " A-fibrinogen " obtained 
from plasma, his " serum fibrinogen " obtained from dog's serum, and 
the " tissue fibrinogens," which he obtained from various organs, all 
owe their action to the nucleo-proteid which they contain. Translating, 
then, the phraseology employed by Wooldridge, the alterations in 
blood plasma, which come under the various conditions above noticed, are 
due to the interaction of nucleo-proteids and fibrinogen. And it would 
appear that, when in the interaction the nucleo-proteids are present in 
relatively small amount, the negative phase is the result ; when in 
large amount, the positive phase. Also that, when added to the 
circulating blood, leucocytes yield but little of their nucleo-proteid to 
plasma, and hence a negative phase is the result ; but, on the other 
hand, when added to plasma in vitro, a larger amount is yielded, and 
coagulation results. A remarkable observation, and one very difficult to 
explain, is the fact that, if the negative phase is once established by the 
intravascular injection of a small amount of nucleo-proteid, artificial 
colloid, or snake venom, a large excess of the same will then not only 
fail to produce the positive phase, but will even strengthen the negative 
phase. It is, therefore, only the initial change which is influenced by 
the relative amounts of interacting material ; and, when once this change 
is established, it does not again become modified. 
Wright's experiments. — Wooldridge further found that under some cir- 
cumstances the amount of fibrin produced was dependent upon the amount 
of tissue fibrinogen or A-fibrinogen (nucleo-proteid) added to plasma. He 
therefore came to the conclusion, since the extent of action was not in all 
cases independent of the amount of these substances, that the action could 
not be looked upon as that of a ferment, although under some cir- 
cumstances the extent of action did appear to be independent of the 
amount of these substances. Wooldridge offered no explanation of the 
different effects obtained with large and small doses respectively, his 
work upon the subject having been cut short by his untimely death. 
It has, however, been continued on the same lines by Wright, 2 who, 
whilst confirming most of Wooldridge's observations, has added 
materially to our knowledge of the conditions under which " tissue 
fibrinogen " or nucleo-proteids produce the negative and positive phase 
of coagulability. Wright states that the extracts of glands containing 
1 Wright found, however, that the number of leucocytes in peptone blood was extremely 
reduced, much more so than is the case in oxalate or magnesium-sulphate blood, and that 
it contains a corresponding! v larger amount of nucleo-albumins, Proc. Roy. Soc. London, 
10th Feb. 1893. 
2 Proc. Roy. Irish Acad., Dublin, 1891, 3rd series, vol. ii. p. 117. 
