THE BEGINNINGS OF LIPE. 35 



vacua ; whilst a similar solution which has been boiled 

 for some minutes does not at all readily become turbid 

 even when exposed to the air, although it will do so in 

 a few hours if some living Bacteria be purposely added. 

 Such facts seem to show, not only that living Bacteria 

 are scarce in the air, but also from the fact that the 

 unboiled solution will rapidly become turbid that the 

 solution originally contained some ferment whose 

 virtues were to a certain extent destroyed by the heat 1 . 

 Destroyed, however, only to a certain extent since 

 the ammonic tartrate and sodic phosphate solution 

 which will no longer become turbid from presence of 

 Bacteria^ will, after a long period, yield Torulte or one 

 of the simplest kinds of Fungi 2 . Destroyed only to a 

 certain extent also, because the citrate of iron and 

 ammonia solution will even yield Bacteria in addition 

 to other organisms, after an exposure to a temperature 

 of I45C, and the solution of ammonic carbonate will 

 also yield Bacteria after an exposure to a still higher 

 temperature for a longer period. Thus the saline solu- 

 tions employed have, perhaps, needed the presence of 

 more unstable matter which might act the part of a 

 ferment, before life-giving changes could be initiated. 



However difficult it may be, at first, to imagine 

 that living things are capable of springing up de nova 

 in a solution of tartrate of ammonia and phosphate of 



1 The ferment must have been originally either in the water, in the 

 crystals, or in both. 



a See Appendix A, pp. i. and ii. 



D % 



