592 THE BEGINNINGS OF LIFE. 



in the quality of an infusion, however induced — 

 whether by the agency of heat or by the addition of a 

 minute quantity of some chemical ingredient — will 

 frequently cause entirely different organisms to appear 

 in altered and unaltered portions which are similarly 

 exposed ^ And yet different portions of the same un- 

 altered solution, when it is highly fermentable, are found 

 at first to yield nothing but Bacteria, under the most 

 varied conditions of exposure to air, or even in 'vacuo. 



The above-mentioned variations in the organic pro- 

 ducts obtainable from different infusions, or from the 

 same infusion after its organic constituents have been 

 slightly modified, are, therefore, now best explicable on 

 the supposition that from these different starting-points 

 living matter comes into existence with initial, though 

 probably inconsiderable, molecular differences of con- 

 stitution, and that these variations lead the respective 

 new-born units to assume different modes of growth 2, 



Again, the fact that lower Infusoria and lower Cryp- 

 togams are to be met with, possessing almost similar 

 forms and characters in the most different regions of 

 the earth, seems to show pretty conclusively that the 



^ See p. 302. 



^ The different results, as regards form and structure, producible by 

 difference in the composition of the aggregating material, have, moreover, 

 been beautifully demonstrated by Mr. Rainey (pp. 60-65) in his experi- 

 ments on the artificial production of calculi — vi^hich he has shown to be 

 modified forms of crystals. The supposition above mentioned would 

 harmonize well with an expansion of Mr, Spencer's hypothesis con- 

 cerning ' psychological units.' (See p. 595, note i.) 



