[NICHOLLS] CALCIUM CONTENT OF THE BLOOD 91 
extract results in a diminution in the amount of calcium in the system. 
In osteomalacia not only are the calcium salts removed from the bones, 
but there is a great increase in the amount eliminated in the urine. 
The influence of the ovaries on this process is referred to above. The 
relationship of the sexual organs in the female to calcium metabolism 
is so remakable that it merits a more detailed reference. 
Blair Bell and Pantland Hick in a suggestive paper! record their 
observations on the connection between menstruation and the calcium 
content of the blood. They find that immediately before the menstrual 
cycle is instituted there is a marked drop in the calcium index, occasion- 
ally preceded by a slight rise. In some cases the calcium dropped to a 
sixth of the previous amount. Coincidently with this, they observed 
that the amount of lime in the menstrual discharge was greatly in excess 
of that in the systemic blood. They further show that the excretion 
takes place mainly by the migration of leucocytes, laden with salts from 
the uterine glands, to the uterine cavity. They note an analogous series 
of events in the case of hens. In the non-laying hen the calcium index 
remains low and fairly constant, in one chart varying from 0.9 to 1.4. 
In laying hens there is a marked drop in the calcium index after laying 
an egg, in one case from 3.2 to 0.5. Microscopical sections of the lower 
part of the oviduct in laying hens showed marked evidences of activity 
of function. They, further, point to the following clinical facts. Ame- 
norrhcea due to general debility is cured and the symptoms relieved by 
the administration of calcium salts. Menorrhagia (not due to local 
pathological lesions) is similarly relieved. They explain the apparent 
paradox in this way. In the first case there is not enough calcium in 
the blood to initiate the process of menstruation. In the latter, there 
is enough lime to set up menstruation but the calcium index does not 
rise fast enough to bring about its cessation. The enlargement of the 
thyroid, before noted, which occurs just before the onset of menstruation, 
the authors in question associate with the fact that the calcium index 
is high at that time. The enlargement of the thyroid which is met with 
in the earlier months of pregnancy they explain as due to the fact that 
menstruation is suppressed, the lime accumulates in the system, and 
the fœtus as yet is unable to utilize all that is provided. They note, 
finally, that they have observed the same enlargement of the thyroid in 
artificial menopause. They conclude that the function of the thyroid 
gland is to stimulate calcium excretion, which usually takes place 
through the uterus, but failing this, by means of the kidneys or bowels. 
It may be observed, too, that while ovulation and menstruation are not 
necessarily correllated functions, the internal secretion of the ovaries is of 
importance in some way causing menstruation, for, as has long been 
? Bell and Hick, loc. cit. 
