266 THE EVOLUTION OF LIFE 
Fig. 38, and no living thing of any kind could 
be discovered in any of the flakes examined. The 
only known cause of this remarkable difference was 
the fact that this A solution had been heated in a tube 
of uviol glass, and had subsequently been exposed to 
light therein. The combined result was this remark- 
able change in the flakes of silica, and the non- 
appearance of any living thing. 
An ordinary tube that had been charged with the 
AA solution and heated as above, was exposed 
to light for six weeks. On examination a large 
amount of silica was found to have been deposited, 
and the flakes were large. They were found to 
contain comparatively few of the organic particles, 
and those that existed were small. Small groups 
of Bacteria were seen, some of them with what — 
appeared to be a Torula corpuscle in their midst, 
as shown in Plate VIII., Fig. 24, A, similar to 
what had been found in some of the earlier tentative 
experiments (see Plate II., Fig. 5). A few separate 
Torule were also seen, one of which, as shown in 
Fig. 25, A, was germinating. 
The inorganic particles were far less abundant in 
this AA solution in common glass than they were 
in the A solution above referred to, in which all 
the conditions were similar except that one solution 
contained rather more silica than the other. These 
facts, as well as that above referred to in reference 
to the extraordinary change produced in the A 
solution when heated in and exposed to light in a 
uviol tube, are important as showing the different 
effects produced by high temperatures upon the 
