196 ORIGIN AND NATURE OF LIFE 



solution is acid, and when this is added to the 

 alkaline sodium silicate, the tendency is to 

 form a mixture of two colloids, viz., colloidal 

 silicic acid, and colloidal ferric hydrate. 

 From this point of view it is of interest to 

 note that the optimal condition at which 

 the experimenter is instructed to aim by 

 Bastian, is that at which a small amount of 

 precipitate appears some time after sterilizing. 

 This empirical direction simply means, to the 

 chemist, that the point is to be aimed at 

 where colloid is formed but not precipitated. 



These experiments as to evolution of organ- 

 isms from inorganic solutions have not been 

 repeated by other observers but such test 

 experiments and others upon similar lines, are 

 now in progress. 



The conditions in these later experiments 

 of Bastian are essentially different from those 

 of his earlier work, a fact which does not 

 appear to have been fully realized by those 

 who have adversely criticized them without 

 attempting their repetition. 



There is one thought which occurs to the 

 mind, and that is, that what might have 

 been expected would have been simple 

 organic bodies in solution rather than micro- 

 organisms. In science the unexpected has, 

 however, a remarkable way of happening, 



