well-recognised fact among physicians. The manifests itself in race, in the differ-
phenomenon
in the
stages of life, and the individual. In India
ent
a
family
well
as
as
familiar to
example is typhoid fever
susceptibility of Europeans non-susceptibility of Hindus and Mahomedans. In the West Indies this peculiarity is
the
and the
exemplified
in the
liability
of the white
race to
marked immunity of the yellow fever and the The young of every disease. this race to
Negro race
are
more
susceptible
to certain
diseases
than the old. The contageous virum of smalland other infectious diseases find pox, measles, their best hosts in children. There are families and
individuals
prone
to become
very prone to
special diseases,
tuberculous, cancerous
or
leprous,
while others have no such tendency. The cause differences have always been a or causes of these matter of
interesting conjecture;
but it is
only
in comparatively recent years that any approach to a scientific explanation based on experimental evidence has been reached. MetschnikofFs theory of Phagocytosis is scarcely more than ten had its starting point not in exyears old, and on man, but in an experimental study
periments of
an
infectious disease caused by a torula in a of Daphnia; the results obtained being
species
afterwards confirmed by further experiments with pathogenic microbes on immune animals. According to Metsclinikoff immune animals re-
sist infection by special activity of the leucocytes which seize the invading bacteria, but it has been urged that there is no evidence to show the bacteria taken np by the phagocytes
that
Oct.
MEDICAL NEWS.
1895.1
have been killed by them. In support of this view Buchner in 1889 experimentally demonstrated that in dogs and rabbits the germicidal power of the blood belonged to the serum, and he attributed the destructive property of the serum " to the presence of proteids which he called AlexHankin in 1892 traced the origin of these proteids or Alexines to the eosinophil granules
ins."
which dissolve in the
serum
producing according
to the extent of their solution a corresponding to bacteria. Von Fodor power of resistance of the serum by this increased resisting power the
of
injection
Calabrese
were
an
while Pansini and by the addi-
alkali,
able to diminish it
tion of uric acid. Vaughan, McClintock and Novy trace the germicidal properties of blood serum to a nuclein derived from the white corpuscles. Thus it would appear that recent investigations tend to show that the resisting element to bacterial disease is in the blood serum, that its origin is from the leucocytes and that an alkaline state of the blood favours the solution of the special protective proteids in these corpuscles. It would be interesting to learn of a comparative examination being made of the blood of