86 ROYAL SOCIETY OF CANADA 
extravasation of blood from the vessels; and in the allied conditions of 
urticaria, chilblain, cedema, and the so-called “lymphatic” headache, in 
which there is a passage out of the plasma only, is so universal among the 
profession that it seems almost heresy to question its propriety and yet 
I find that opinions are by no means unanimous on this point. For 
example, in a recent paper! read before the Royal Academy of Medicine 
in Ireland, Prof. B. J. Collingwood takes issue with the current belief 
that calcium chloride acts as a hemostatic by increasing the coagu- 
lability of the blood. His experiments, conducted in vitro, afforded no 
warrant for concluding this to be the case. He thinks that the clinical 
effect attributed to this salt must be due to some other property. In 
the discussion that followed, Prof. McWeeney suggested that the 
hemostatic power of the salt was due to its action as a general vaso- 
constrictor. In this latter regard, it may well be doubted whether such 
action on the vessels would be prolonged sufficiently to be effective, and 
some well-known surgeons, when they wish to obtain a hemostatic 
action previous to an operation, have given up the use of calcium in 
favour of injections of an alien serum. An Italian observer, Ciuffini,? 
has come to the same conclusion as Prof. Collingwood. Such being the 
case, we may well pause to examine into the reason for the faith that is 
within us. With this end in view I have undertaken an investigation at 
the bedside into a number of different ailments, making a parallel series 
of observations on the calcium content of the blood, the coagulation 
time, and the degree of the blood pressure, hoping thereby to gain a 
footing on some firmer ground. For the purpose I have selected a 
class of diseases in which there seems to be a notable deviation from the 
normal in the matter of the coagulation power of the blood: To wit, 
typhoid fever, in which blood pressure is low and there is little tendency 
to the formation of fibrin; lobar pneumonia and acute rheumatism, in 
which fibrinous exudates are the rule and are well-marked: obstructive 
jaundice, in which there is a notable tendency to hemorrhages; purpura; 
pernicious anæmia; arteriosclerosis; Bright’s disease, &c. I soon 
realized, however, that an investigation on the lines I have just indi- 
cated would be of little value unless controlled by other factors. Of 
prime necessity is a knowledge of the laws governing calcium metabolism 
and the ordinary mechanism regulating blood pressure. We may use- 
fully, therefore, pass in review what is the present state of things in 
regard to these subjects. 
In all individuals having a separate existence the calcium in the 
system is derived directly from the food. The developing embryo 
obtains it from the maternal tissues, but in the last resort of course 
! Collingwood, Abstract in Brit. Med. Journ., 1; 1910; 507. 
? Ciuffini, I] Policlinico, 16; 1909; 12. 
