SUSCEPTIBILITY TO DISEASE. Susceptibility is

a

or

non-susceptibility

to disease

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

white, black, brown and yellow their

germicidal their chemical physiology sibly

races

as

regards

activities and the differences in

new

and

pathology. Posinvestigation light on a subject

facts derived from this

would throw considerable

which, notwithstanding

the

great advances

recent years, still remains obscure.

in

391

Susceptibility to Disease.

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