6 S. H. HUTNER 



not the ENIACs incarnate of popular legend even in the act of 

 choosing experimental materials. 



Algae and Tissue Culture 



The foregoing generalizations may be lent some concreteness 

 by considering a sector of the frontier of research which, on the 

 surface, shows very little connection with the growing of algae. 



Tissue culture provides an unusally direct approach to the 

 study of cancer. Factors that determine the differentiation and 

 controlled growth of cells and tissues may eventually become 

 isolable as conditions for in vitro growth become better defined. 

 The mode of action of carcinogens is representative of the kind 

 of problem that can probably be attacked more successfully this 

 way than by in vivo studies. Earle et al. (1943) discovered that 

 apparently normal fibroblasts of mice, when grown in a medium 

 of chicken plasms, horse serum, and chick-embryo extract, spon- 

 taneously yielded cultures giving rise to sarcomas when injected 

 into mice. It is obviously of the highest importance that the cause 

 of this transformation be identified. This is likely to be an easier 

 task if the cells can be grown on a synthetic medium. The most 

 nearly adequate synthetic medium for tissue cultures appears to 

 be one elaborated by Morgan et al. (1950) for chick embryo tis- 

 sue. That this medium is incomplete is shown by its inability to 

 allow growth of subcultures. One of the compounds that might 

 be helpful in supplementing this medium is vitamin B12, the anti- 

 pernicious anemia factor. There is a close agreement between the 

 specificity of the B12 requirement of the algal flagellate Euglena 

 gracilis and that of the chick, rat, and man (Hutner et al., 1949, 

 1950). A more energetic pursuit of the growth factors for Eu- 

 glena might have made vitamin B12 available sooner for use in 

 tissue culture as well as in practical nutritional therapy. The 

 development of the basal medium used for the assay of B12 by 

 means of Euglena was guided by the early studies of E. F. Hop- 

 kins on the inorganic requirements of Chlorella. The beginnings 

 of work on the culture of Euglena by other workers and the 

 writer was motivated for the most part by a desire to explore the 

 taxonomic and phylogenetic relationships between the chlor- 



