THE BEGINNINGS OF LIPE. 433 



an organic solution in which colloidal substances are 

 dissolved. 



But just as the combinations which constitute living 

 matter are superior in complexity to, and more destruc- 

 tible by heat than, colloidal compounds, so are colloidal 

 compounds themselves broken up and more or less 

 destroyed, by an amount of heat which will leave many 

 crystalloids unaltered. The degree of heat necessary 

 to decompose different complex colloids is, of course, 

 subject to an amount of variation which does not 

 admit of previous predication. As a rule, however, 

 the more intense the heat to which a solution has 

 .been subjected, the more has the complex compo- 

 sition of the dissolved substances been impaired, and 

 the less is the solution calculated to be one in which 

 the new combinations initiative of living matter could 

 arise. The de novo origin of living matter in a solution 

 is possible at any period, after the destruction of all 

 its pre-existing living things, provided the heat 

 employed has not been so extreme as to break up 

 its colloidal compounds, or such other unstable com- 

 binations as may be capable of conjointly yielding so 

 high a product. The number of successful results, 

 however, naturally diminishes, according as one em- 

 ploys, either more destructible compounds or higher 

 temperatures and less destructible compounds. 



So that however meagre the chances may seem 

 for the occurrence of nature's subtlest material com- 

 binations within even ordinary experimental flasks (as 



VOL. i. F f 



