THE WONDERS OF LIFE 



tophyta and protozoa) the constructive force of the 

 elementary organism, the individual cell, determines the 

 symmetry of the typical form and the special form of its 

 supplementation; but in the histons (both metaphyta 

 and metazoa) it is the plasticity of the tissue, made up of 

 a number of socially combined cells, that determines this. 

 On the ground of this tectological distinction we may 

 divide the whole organic world into four kingdoms (or 

 sub-kingdoms), as the morphological system in the 

 seventh table shows. 



In respect of the general science of fundamental 

 forms (promorphology), the most interesting and varied 

 group of living things is the class of the radiolaria. All 

 the various fundamental forms that can be distinguished 

 and defined mathematically are found realized in the 

 graceful flinty skeletons of these unicellular sea-dwelling 

 protozoa. I have distinguished more than four thou- 

 sand forms of them, and illustrated by one hundred and 

 forty plates, in my monograph on the Challenger radio- 

 laria [translated]. 



Only a very few organic forms seem to be quite 

 irregular, without any trace of symmetry, or constantly 

 changing their formless shape, as we find, for instance, 

 in the amoebae and the similar amoeboid cells of the 

 Plasmodia. The great majority of organic bodies show 

 a certain regularity both in their outer configuration and 

 the construction of their various parts, which we may 

 call "symmetry" in the wider sense of the word. The 

 regularity of this symmetrical construction often ex- 

 presses itself at first sight in the arrangement side by 

 side of similar parts in a certain number and of a certain 

 size, and in the possibility of distinguishing certain ideal 

 axes and planes cutting each other at measurable angles. 

 In this respect many organic forms are like inorganic 

 crystals. The important branch of mineralogy that 

 describes these crystalline forms, and gives therr^ 



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