19 



the Carnegie Institution in his Jan. 1, 1936 address be- 

 fore the American Association for the Advancement of 

 Science : 



The present restrictive influence of organized 

 religion on the teaching of the best of biology is in- 

 tolerable. (Science, Jan. 24, 1936.) 



Notwithstanding these unfavorable conditions, there 

 have been a few investigators who have done consider- 

 able work on this problem during recent years, and fore- 

 most among these have been A. L. Herrera in Mexico, 

 and W. D. Francis in Australia. Although both of these 

 investigators have been working on the same problem, 

 they have tried to solve it by entirely different methods, 

 and with widely different results. Herrera used 36% 

 formaldehyde solution (3 grams) as the principal source 

 of carbon, whereas Francis used atmospheric carbon 

 dioxide. Herrera formerly used ammonium sulphide 

 with oxides of nitrogen, and more recently ammonium 

 thiocyanate (1.5 grams) as the source of nitrogen and 

 sulphur, whereas Francis used the following mixture : 



Herrera obtained a multitude of life-like and actively 

 moving organisms closely resembling natural protozoa 

 and exhibiting in every detail the phenomenon of mitotic 

 cell division, whereas Francis did not obtain any actively 

 moving organisms or anything resembling natural pro- 

 tozoa. On the other hand Francis claims to have ob- 

 tained synthetic proteins whereas Herrera has found 

 only amino acids and starch. 



