LIFE 



saturated medium only up to a definite size, which 

 is determined by its chemical-molecular constitution. 

 When this limit is reached a number of small crystals 

 appear on the large one. Ostwald, who has made a 

 thorough comparison of the process of growth in crystals 

 and monera, especially notices the striking analogy 

 between a bacterium (a plasmophagous moneron) 

 growing and multiplying in its nutritive fluid and a 

 crystal in its matrix. When the water slowly evaporates 

 from a supersaturated solution of Glauber-salt, not only 

 does a crystal slowly grow in it, but several young 

 crystals appear on it. The analogy with the bacterium 

 multiplying in its nutritive fluid can even be followed as 

 far as its permanent forms or "spores." This quiescent 

 form is assumed by the bacterium if its supply of food 

 is exhausted; if fresh food is added, the multiplication 

 by cleavage begins again. In the same way the crys- 

 tals of Glauber-salt begin to decay when the solution 

 is evaporated; they lose their crystal water, but not 

 their power of multiplication. Even the amorphous 

 powder of the salt causes again the formation of new 

 watery crystals when put in a supersaturated solution. 

 But the powder loses this property when it is heated, 

 just as the dormant forms (or spores) of the bacteria 

 lose their power of germination. 



The exhaustive comparison of the growth of crystals 

 and monera (as the simplest forms of unnucleated cells) 

 is important, because it shows the possibility of tracing 

 the vital function of reproduction — which had usually 

 been regarded as a quite special "wonder of life" — to 

 purely physical conditions. The division of the growing 

 individual into several young ones must necessarily take 

 place when the natural limit of growth has been passed, 

 and when the chemical composition of the growing body 

 and the cohesion of its molecules allow no further en- 

 largement by the assumption of new matter. In order 



43 



