316 Scientific Proceedings (123). 



years, each fragment generally doubling its volume in 48 hours. 

 In 10 years, more than 30,000 cultures have been derived from a 

 fragment of heart less than 1 cubic millimeter in size. This dem- 

 onstrates first, that the cells transform the food stuffs in their 

 medium into protoplasm. Second, under the conditions of the 

 experiments, the cells are no longer subject to the influence of time, 

 as they are when living within the organism, and demonstrate that 

 they are potentially immortal. The cells have now exceeded the 

 average life of chickens, which disposes of criticisms on this point. 



Pure cultures of cells are important in studying biological 

 problems. The strain responds readily to changes in the compo- 

 sition of the culture medium by modifying its rate of proliferation. 

 By perfecting the technique, it could be used as a reagent for 

 detecting substances contained in the humors which have the 

 power of activating or decreasing the rate of cell proliferation, 

 and further, to investigate the interactions of the cells and their 

 medium, which are still incompletely known. 



144 (1891) 

 Bio-radiological studies. 



By HERBERT RUCKES and ARTHUR W. FUCHS (by invitation). 



[From the Department of Biology, College of the City of New York.] 



Animals in which arteries, veins and ducts of various organs 

 are injected with salts of heavy metals, such as mercury, barium, 

 lead, gold and silver are skiagraphed and subsequently studied 

 in either plane view or by means of stereoscopic roentgenograms. 

 The method is especially valuable for the study of animals from 

 the view point of comparative anatomy, Such preparations 

 show clearly first, the general construction of the arterial or ven- 

 ous system and secondly the minute ramifications of the respec- 

 tive arteriole systems on and within the organs. Probably the 

 most valuable use that this method has is in the study of develop- 

 ing systems and ducts in embryos. Here the homologies of the 

 embryonic blood vessels and the adult arteries and veins can 

 readily be demonstrated. 



