100 FACTORS OF EVOLUTION 



Evolution among the lowest kinds of living things. How far up in 

 the scale of life it remains an all-powerful cause must for the 

 present remain unknown. Certainly, my observations compel me 

 to believe that organisms as high as Ciliated Infusoria very 

 frequently derive their form as a direct outcome of molecular 

 changes in masses of living matter derived from wholly different 

 sources, as I shall show later on. This 'organic polarity' is 

 probably all-powerful also among all kinds of Protophyta and 

 Protozoa — in many of which the wonderful symmetry of their 

 forms and markings is strongly suggestive of the determining 

 influence of polarities, and the production of a kind of organic 

 crystallisation. Among Protophyta look, for instance, at the forms 

 of Desmids ; at the forms and surface patterns of Diatoms ; and 

 among other Algae at the extremely symmetrical patterns or modes 

 of grouping of the cells in such forms as Coleochoete, Pediastrum 

 and Volvox. While among the Protozoa evidence of the same 

 kind of forces having been at work is to be found in the single 

 chambered shells of the Arcellinse, and still more plainly in the 

 beautiful forms of Foraminifera, and of the Radiolaria. Speaking 

 of the latter creatures Haeckel says,' " All the various fundamental 

 forms, that can be distinguished and defined mathematically, are 

 found realised in the graceful flinty skeletons of these unicellular 

 sea-dwelling protozoa. I have distinguished more than 4,000 

 forms of them, illustrated by 140 plates, in my monograph on the 

 Challenger-radiolaria. ' ' 



No reasonable person can suppose that any distinct advantage 

 could accrue to the possessors from these infinitely varied shapes 

 and surface patterns. And if so, the cause of their origin must 

 be something altogether outside the pale of natural selection, upon 

 which Weismann doubtless would wish us to rely here, as in all 

 other respects. 



But this same cause which may be all-powerful in determining 

 the actual shapes and superficial markings of the lowest forms 

 of life, is one that cannot fail to be operative as a contributing 

 morphological cause in altogether higher forms of life, and thus 

 in part to account for the symmetry displayed in the forms of 

 plants and animals generally — and especially for the radial or 

 bilateral symmetry of the latter. For as Bateson points out,' 

 symmetry is "a character whose presence among organisms 



' "The Wonders of Life," 1904, p. 178. 



= " Materials for the Study of Variation," 1894, p. 22. 



