Evening star., 1935-06-08
STARS, MEN AND ATOMS
Notebook of Science Progress in Field.
Laboratory and Study.
BY THOMAS r. HENRY,

Production in rabbits and guinea
pigs of typical silicosis-the pseudo
tuberculosis" common among indus
trial workers employed continuously in
dusty atmospheres-has just been an
nounced by the Public Health Service.
In order to obtain the syndrome of
the malady in the experimental ami
mails 1t was necessary to keep them
in an atmosphere containing quartz
dust eight hours day and six days
a week for a year or more. Thus they
were subjected to essentially the same
environment as the factory worker,
quarry employe or miner. The air
the creatures breathed contained ap-
proximately 1000 ,000, 900 dust particles
per cubic foot. Most of these particles
were less than thousandth of a mil
limeter In diameter-so small as to be
invisible.
The work was conducted at the
Saranac Laboratory for the Study Of
tuberculosis, at Saranac Lake, N. Y,
by DR.. Leroy w. Gardner in co-opera-
ton with the once of Industrial Hy-
giene Of the Public Health Service
For the first time there. is now avail
able complete picture Of the progress
of the disease, which has become an
increasingly serious health problem for
industry. It Is characterized by the
formation of nodules in the lymphoid
tissues of the lungs which often are
not distinguished from tuberculosis
LESSONS. The disease is progressive
after the victims have stopped breath
ing dust, Is often mistaken for tuber-
culosis, although the tubercle bacillus
Is not present, and quite frequently
causes death.
The experiments with animals re-
vealed the curious physiological reac-
tions associated with the malady and
the differences in its progress. depend
ing on the kind Of dust inhaled. 1t is
due especially to the inhalation of MI
croscopic particles of pure quartz.
These particles are ingested by the
phagocytes, the wandering white blood
cells which are the scavengers of the
body. Apparently these scavenger cells
are stimulated by such q meal, per-
haps due to q chemical reaction be-
tween them and the quartz. They
migrate rapidly to the nearest mass
of lymphoid tissue in the lungs, thus
concentrating the dust in the lymph
nodules. But the quartz Is poisonous
and eventually destroys the blood cells
which have swallowed the particles.
They are released, to be taken up by
other phagocytes. These soon suffer
the fate of their predecessors. BY q
constant repetition Of this process
both the irritating dust and the hy-
pohetical products of cellular activity
upon it are liberated In high concen-
trations in intimate contact with the
connective tissue elements OF the
lymph nodule. They proliferate and
form a lesion which is hardly distin-
guishable at first from q tubercle
associated with tuberculosis.
A refutation Of the finding that
there Is an intimate relationship be-
tween length of life and speed of
growth Is presented In o report to
the National Academy Of Scienes by
Drs. H. G. Sherman and H. L. Camp
bell Of Columbia University.
They fed rats on standard diets,
leaving only two variables es--individual
growth impulse and individual con-
stitution predisposing to longer life.
Basing their conclusions on the life
histories Of more than 500 such anil
mails, they decided that the chances
are more than 1000 to ] that the
variations. In rate Of growth and
length Of life are Independent rather
than interdepe: 1T.
Among indivioi,'Ii Of the same
sex and the same heredity on the
same normal diet" they conclude,
those who grew faster and those who
grew more slowly had equally TODD
prospects Of : long life. II Is also
svidsnt that csrtain differences n