Li'iiirle Laljuiatorics. Jin-. 



THE CULTURE OF IMMORTAL CHICKEN TISSUE IN THE LABORATORY 



In 1912 Dr. Alexis Carrel of the Rockefeller Institute removed tiny pieces of heart 

 muscle from a chicken embryo still inside the egg shell, at about the ninth or tenth 

 day of hatching. He placed these fragments in a nutritive medium, kept at a suitable 

 temperature and supplied with air. Every two days the growing piece doubled in 

 size; it was divided, and a part placed in a fresh medium. This has been going on 

 for all those years. Most of the new growth has, of course, been thrown away; if 

 all had been allowed to grow, there would not have been room enough for that 

 chicken heart in all the world 



It has been possible in the laboratory to keep a part of an animal "alive" 

 without regeneration. There are the fragments of a turtle's heart which 

 Loeb kept beating away for weeks (see page 302). Even more striking are 

 the experiments of Alexis Carrel (1873- ), who started cultures of 

 chicken tissue that have been kept going for over thirty years (see illustra- 

 tion above). We may consider these tissues as "alive", for they grow and 

 produce more cells like themselves. But they are hardly living chicken. 

 They can do nothing that is typical of the life of a chicken. The growing 

 lump is not a whole, although it continues to carry out life-activity in part. 



With the assistance of Colonel Charles A. Lindbergh, Carrel later de- 

 veloped a more complex apparatus which supplies a rather large piece of 

 tissue, or even an entire organ, with food and air, maintains a suitable tem- 

 perature, and removes the products of metabolism. If we had a whole set of 

 such organs, even all the organs of any particular animal, we still should not 

 have a living animal — a chicken or a dog. 



These "cultured" cells or organs are unable to supply themselves with 

 food, air, or water. They cannot keep themselves warm. They cannot pro- 

 tect themselves. They cannot develop, but merely continue to grow only as 

 material is supplied them by the laboratory attendants. 



To be sure, there are species of living things that depend in a similar 

 way upon others. There are, for example, parasites living in the bodies of 

 larger organisms, where they find the materials and conditions essential for 



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