The times dispatch. [volume] (Richmond, Va.) 1903-1914, 1913-09-21

as the composition of the culture
medium was not modified o
How the medium affected the tie
of pro!iferation, or cell-reproduction,
was studied in two series of expert
ments. In the first series DR.. Carrel
placed fragments OF tissue of known
activity in media Of different COM
positions. In the second series strains
Of cells OF varied conditions OF
activity were placed in media OF the
same composition. BY measuring
The growth Of the fragments of It's.
sue which had been living under
these different conditions for several
genera tons IL was possible to ascer-
tain IN what manner the media af-
!ected the development of the tissue.
AS result of these experiments
Dr. Carrel drew the following con.
ciusions:"
When connective tissue cells have
been cultivated for certain length
OF time In medium which has been
repeatedly changed, definite rela-
ton arises between the rate OF
growth OF the cells and the conpo
s!tion OF the medium.
IT is possible. by adding to the
culture medium given quantity of
certain substances. such as embry-
onic juices, TO foresee the extent TO
which fragment OF tissue COMPOSED
OF given strain of cells will in
crease III Il given time. The rate OF
growth Of strain OF cells can be &C.
tolerated or retarded by the addi-
ton to the medium OF activating or
retarding substances.
a knowledge of the Characters.
ties OF the growth of connective It's
sue described has led 20 a new re-
su!t-the indefinite proliferation' OF
strain Of connective tissue cells
outside of the organism.
The strain OF connective tissue
Originally obtained from a fragment
or chick embryo heart, which had
been pusating in vitro for 104 DAYS.
was still actively alive after sixteen
months OF independent life and more
than $50 passages. "a passage, 1t
may be explained. Is transfer of the
cell from one medium to another. a
process the necessity for which is
hereafter explained.)
The rate of proliferation of the
connective tissues sixteen months
old equalled and even exceeded that
OF fresh connective tissue taken from
an elSntday-Oid EN- bryO.
1t appears, therefore, that time
has no effect on the tissues isolated
from the organism and preserved by
means of the technique above de-
scribed.
During the sixteenth month of life
In vitro the cells increased rapidly
in number and were able in a short
time to produce a quantity of new
tissue. This fact, therefore, definite
ly demonstrates that the tissues were
not In a state Of survival, as was the
case in certain earlier experiments,
but in condition of real life, since
the cells of which they were COM
posed, like heterogeneous, multi.
piled Indefinitely in the culture me-
dunn
There is a great deal of sienif-
canoe In DR.. Carrots observation that
the rate Of proliferat:on of the con-
Eectlve tissue sixteen months old
not only equalled but exceeded that
or fresh connective tissue taken from
an eight-day-old embryo. 1t indicates.
indeed, that even at this early stage
In the study OF prolonging cellular
lie, scientists have been able to pro-
duce medium which, If anything.
improves upon the medium In which
nature grows cells. This Is due, of
course. 80 the fact that the medium
used by the scientists in their exper-
iments is protected to great extent
from the poisonous substances which
harass cells in the living organism.
In the course Of these experiments
1t appeared, of course, that the proc
ess of growth among the cells In
vitro produced, as II does in the
parent organism, certain poisons.
These catabolic substances, as they
are called, accumulate in the human
system and are responsible for the
death of human cells. To protect the