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NATURAL SCIENCE: 



A Monthly Review of Scientific Progress. 



No. 51. Vol. VIII. MAY. 1896. 



NOTES AND COMMENTS. 



Mechanical Symmetry in Living Matter. 



IN the various attempts to explain the shapes and structures of 

 animals, one of the most curious recurrences is a comparison 

 between crystalline structure and organic form. The forms of 

 crystals depend upon the forms of the individual molecules, or groups 

 of molecules, of which the crystalline bodies are composed, and upon 

 the strains and stresses by which the molecules adhere together. The 

 symmetry is the necessary outgrowth of the constitution and nature of 

 the crystalline matter. Repeated attempts have been made to show 

 that there may be a connection between the forms of animals and the 

 constitution and nature of the supposed equivalent molecules, or 

 groups of molecules, of which they may be composed. Some time 

 ago we noticed an interesting volume by Dr. Haacke (Natural 

 Science, vol. v., p. 66), in which he tried to show that the different 

 shapes of animals depended upon different kinds of protoplasmic 

 molecules. We have now received from Arturo Soria y Mata a 

 pamphlet in which a similar theory is ingeniously elaborated. It is 

 entitled Ovigen Poliedvico de las Especies (Madrid : Succesores de 

 Rivadeneyra, Paseo de San \'icente, 20, 1894), and it attempts to 

 show that organic forms may be reduced to aggregates of regular and 

 irregular polyhedra. 



We cannot follow the author at length into his curious enquiry. 

 It seems to us to have been established that protoplasm, the basis of 

 living things, is not a substance, but a mixture, and from the physical 

 point of view we regard it as certain that no living body is composed 

 of equivalent particles. It must be remembered, however, that the 

 appearance of symmetrical patterns may come by the arrangement of 

 dissimilar materials. A kaleidoscope elaborates regular and com- 

 plicated patterns from dissimilar fragments of paper, glass, tinsel, 

 and so forth. The pattern is produced by the complicated optical 

 repetitions of the dissimilar units, each unit and the whole irregular 

 group being repeated by mirrors. Now cell-multiplication produces a 

 result closely similar. The multiplication of cells from a growing- 



