18 life's beginning on the earth 



which seems to indicate that the building forces of living 

 growth and of non-living crystallization have some rela- 

 tionship. Here is one of the links between the non-living 

 and the living world — just a group of plain salt crystals, not 

 a bit of life in them, yet manifesting an ambitious tendency 

 to resemble the outline of real living things. 



One possible explanation for this resemblance may be 

 that gelatin or starch are materials of organic origin ; gelatin 

 is extracted from bones while starch is a plant product. 

 No wonder the addition of such organic materials alters 

 crystalline growths so that they resemble organic forms! 

 Some life-like property may still reside in this organic ma- 

 terial. An objection to this explanation is that we can 

 obtain a similar effect with a purely inorganic slimy or 

 gelatinous system such as silica gel. Life-like crystalline 

 structures may arise in the entire absence of any material 

 derived from organisms. 



But when we add different materials to the growing 

 crystals we find that each of them has its own way of chang- 

 ing the appearance and arrangement of the crystalline 

 aggregate. 



2. pfeiffer's method of "sensitive crystallization" 



The character of the added material determines the type 

 of the alteration of crystalline aggregates even if only traces 

 are added. If extracts freshly prepared from plants or 

 blood of animals or men are added to the growing crystals, 

 striking new forms appear. These forms are so varied that 

 it takes almost a life-time's work to thoroughly study their 

 appearance. 



Ehrenfried Pfeiffer, a Swiss research chemist, devoted 

 years of intensive studies to these forms, some of which 

 are reproduced here with his permission (Figs. 6-12). 

 These pictures reveal astounding facts. They show how a 

 copper salt which crystallizes irregularly when nothing is 



