MODES OF ORIGIN COMPARED 55 



Micrococci, Staphylococci, Streptococci, etc.), and Torulas merely 

 represent the most prevalent forms which specks of new-born 

 living matter are prone to assume;' and in conformity with this 

 view, it may be stated that all intermediate shapes are frequently 

 to be seen between the various forms, just as all intermediate 

 conditions are to be seen between the smallest Bacteria of some 

 highly fermentable infusion, and the larger Vibrio-like or Leptothrix 

 forms which are frequently met with in other fluids. 



The opinion was formerly held that Vibriones and Leptothrix 

 are higher organisms than Bacteria, and that Torulse are higher 

 than either. Both these views, however, are equally devoid of 

 any real foundation. 



It is well known that the more rapidly crystalline matter sepa- 

 rates from a solution, the greater is the number and the smaller the 

 size and perfection of the crystals which appear. And similarly 

 it may be found that the most fermentable solutions swarm rapidly 

 with inconceivable numbers of small Bacteria ; though if a drop or 

 two of acetic acid has been added to another portion of the same 

 infusion, it will not become turbid till many hours later, and the 

 Bacteria which are present in the first scum may be much larger 

 and such as are generally termed Vibriones or Leptothrix. In 

 other cases, highly fermentable fluids which have been subjected to 

 the influence of very high temperatures (270° F and upwards) will, 

 even when exposed to the air, yield neither Bacteria nor Vibriones 

 — though Torulae will appear after a time, often as a sediment, and 

 multiply more slowly. 



Now with reference to such observations, the following con- 

 siderations must be borne in mind. A highly fermentable solution 

 is in one respect exactly comparable with a supersaturated saline 

 solution. Both contain chemical elements whick we may suppose 

 to have a strong tendency to combine, and in both cases the 

 products of combination are insoluble — particles of crystalline 

 matter appear in the one case, and particles of living matter in the 

 other. But the living matter differs essentially from the crystalline 

 matter by reason of the complexity of its constituent molecules, and 

 its consequent more marked instability. This capacity for free 

 internal molecular movement, which is one of the most distinctive 



' Under other conditions, of course, we may have the simplest Algae appearing 

 as non-nucleated, blue-green specks of protoplasm (the Chromacea) ; and under 

 others still the simplest Amoebas. All these forms, however, are just as varied 

 and mutable as we shall find the Bacteria to be. 



