NATURE STUDY IN SCHOOLS. 171 



pieces of many sizes all fit together with a mathematical precision which is 

 truly wonderful. And more remarkable still is the fact that all of these pieces 

 in combination form a structure, the design of which must have been precon- 

 ceived. A man who, with similarly formed pieces of stone, but of a larger 

 size, could construct a habitation of a design like that in which this species 

 of amoeba lives, and do it as well would take high rank as an architect and 

 stone mason. 



No two of these amoebae gather material which is exactly alike, but all 

 construct habitations so nearly alike that is quite easy to distinguish the spe- 

 cies which live in them by the form of the coverings. The shells of one species 

 being as different from those of another, as are the shells of different species 

 of mollusks. 



Fig. 77. 



Crown&d Amoeba. Diffuigia corona Wallieh. From a pond in Auburndale, Mass. Aug. 3, 1699 



Some may consider that the amoebae labor instinctively, making habita- 

 tions exactly as their ancestors have made them for many generations, and that 

 the forms of the animals themselves within the shells are as specifically dif- 

 ferent as are the forms of the animals in the species of shell formed by mol- 

 lusks. While this may be true to a certain degree in regard to the forms of 

 the animals, and I have but little doubt but what we should find specific 

 differences among them could we manage to study them, it must be kept in mind 

 that there is a wide difference between the unconcious secretion of a shell by 





