THE BEGINNINGS OF LIFE. 363 



rated in pre-existing organisms, is, at present, absolutely 

 necessary for the de novo origination of living things , 

 or whether, in fact, these may arise, more or less 

 directly, by changes taking place in an aggregation of 

 new-formed molecules of an organic type \ 



At present, however, no special precautions have 

 been taken to ensure the purity of the chemical sub- 

 stances employed. These may, and sometimes did 

 undoubtedly contain organic impurities, so that the fol- 

 lowing experiments are simply quoted as instances in 

 which more or less acid fluids, containing at all events 

 a very large proportion of saline ingredients, have 

 proved productive of living organisms when treated in 

 the way already described. 



SERIES b. Saline Solutions having an acid reaction. 



Experiment i. A closed flask containing a solution 

 of ferric and ammonic citrate 2 in distilled water (gr. x. 

 to |j.) was opened 29 days after it had been hermetically 

 sealed. 



A small amount of powder-like sediment had gra- 

 dually collected at the bottom of the flask, though there 

 was no general turbidity of the fluid. Before the flask 

 was opened it was ascertained that the vacuum was still 



1 These having themselves arisen by the combination of some of the 

 dissociated elements of the saline substances employed. 



2 Some of the purest that could be obtained, from Messrs. Hopkin 

 and Williams. 



