452 THE BEGINNINGS OF LIFE. 



watch-glass as soon as its upper surface was wetted. This 

 solution contained no carbon (see Appendix A, p. x). 



Experiment 1. A solution containing twelve grains of 

 iron and ammonic citrate (mixed with a few very mi- 

 nute fibres of deal wood) in one ounce of distilled water. 



The flask was opened at the commencement of the 

 seventh week from the date of preparation. It was 

 exposed to sunlight for about eight days during the last 

 fortnight, though previous to this the amount of sedi- 

 ment had gradually increased. After the second or 

 third exposure the previously dark brown fluid became 

 fluorescent black to reflected, but olive-coloured to 

 transmitted light. There was also a brownish deposit 

 on one side of the tube. When the flask was opened 

 it was found that the vacuum was almost wholly 

 impaired, by an internal evolution of gas. On 

 microscopical examination of a drop of the fluid (con- 

 taining sediment), multitudes of granules, separate and 

 aggregated into flakes, were seen. There were no dis- 

 tinct Bacteria, though large numbers of the rounded and 

 ovoid organisms similar to those met with in Exps. 9 

 and 12, were intermixed with the granules. They were 

 partly separate, partly in groups of fours and eights. 

 They varied considerably in size, and also in colour 

 some being decidedly greenish, and others quite yellow 

 and faded. In the granular aggregations, different stages 

 in the growth of these Desmid-like bodies were to be 

 recognized. What appeared to be short Leptothrix fila- 

 ments issued from some of the granular masses. 



