574 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1910. 



the body. At this time Carrel was engaged in the study of the laws 

 of cicatrization of tissues and cutaneous wounds of mammals, and 

 resolved to use for that purpose the method of Harrison. Then 

 Burrows, under the guidance of Prof. Harrison himself, adapted 

 the method to the cultivation of tissues of the chick embryo; that is, 

 of a warm-blooded animal. Then, in September, 1910, at the Rocke- 

 feller Institute we succeeded in cultivating in vitro, adult tissues of 

 mammals. 



We used at first the culture method of Harrison, that is, of small 

 pieces of tissue suspended in a hanging drop of plasma. Afterwards 

 we developed a method of culture on a plate, which permitted us to 

 grow large quantities of tissues. It became therefore possible to 

 observe many new facts. 



It was found at first that almost all the adult and embryonic 

 tissues of dog, cat, chicken, rat, and guinea pigs could be easily culti- 

 vated in vitro. According to their nature these tissues generate con- 

 nective or epithelial cells, which grow into the plasmatic medium in 

 continuous layers, or in radiating chains. The tissue fragments may 

 surround themselves completely with dense new tissue, or, on the 

 contrary, the new cells may spread over the surface of the medium. 

 We observed the direct division of the nuclei during the life of the 

 cells, and many karyokinetic figures in the fixed and stained cultures. 

 Other experiments showed that the life in vitro of the tissues, which 

 varies from about 5 days to about 20 days, can be prolonged by 

 secondary and tertiary cultures, and that a new generation of 

 thyroid, splenic and sarcomatous cells can be obtained from cells 

 which have developed outside the body. We succeeded quickly also 

 in cultivating malignant tissues such as the Rous chicken sarcoma, 

 the Ehrlich and Jensen sarcoma of the rat, a primary carcinoma of 

 the breast (dog) and two human tumors, a sarcoma of the fibula, and 

 a carcinoma of the breast. A culture in vitro of the Rous sarcoma 

 transplanted into a chicken caused the development of a sarcoma. 

 Meanwhile the method has been applied successfully in the laboratory 

 of Prof. MacCallum by Drs. Lambert and Hanes, who cultivated 

 the Ehrlich sarcoma of the rat. We applied also the method of 

 cultivation of tissues in vitro to several problems of the redintegra- 

 tion of normal tissues and of the biology of malignant tumor. 



The results obtained in this and other laboratories are already too 

 numerous to be described in this article. We will indicate only the 

 technique, the general characters of the cultures, and some of the 

 applications of this new method. 



II. TECHNIQUE. 



The new technique consists essentially in depositing small frag- 

 ments of living tissues in fluid plasma or in an artificial medium. 

 The cultures belong to three types — the small cultures in a hanging 



