The Permanent Life of Connective Tissue outside of the Organism

PLATES 53 AND 54. In previous articles I it has been demonstrated that connective tissue cells grow actively outside of the organism for more than four months and thane a fragment of heart still pulsates after more than ioo days of life in vitro. The purpose of this article is to describe the continuation of these experiments. The cultures of connective tissue on which Dr. Carrel made his observations were derived from sixteen small fragments of heart and blood vessels, extirpated on January 17, 1912, from chick embryos, seven to eighteen days old. These sixteen cultures did not grow actively. Several accidents occurred, and in March, 1912, only five cultures survived. After some modifications in the technique growth became more active. The mass of the new tissues increased rapidly. The tissues were divided and subdivided. In May, 1912 , twenty-five to thirty cultures, derived from the few surviving cultures, were growing actively. The size of the piece of tissue contained in each culture increased very much during the latter part of May, 1912. Large necrotic areas appeared in the center of the tissues, and the growth now became less active. I took charge of these cultures on June I, 1912. They were washed in Ringer solution and transferred to a fresh medium every second, third, or fourth day, according to the technique described by Dr. Carrel. 2 The growth was slow and several bacterial infections occurred, so that on July I only five cultures survived. These, however , were growing actively. As the fragments were very small it was not possible to divide the tissues. In the beginning of Sep-tember they were in good condition (figures I and 2). Technical accidents caused the loss of several cultures, and on September 2 5 only one culture survived. This culture arose from a fragment of connective tissue derived indirectly from the fragment of heart *