IX] OF SNOW CRYSTALS 695 



contrary, in a little pinch of deep-sea mud or of some fossil "radio- 

 larian earth," we shall probably find scores, and it may be even 

 hundreds, of different forms. Moreover, the radiolarian skeletons 

 are of quite extraordinary delicacy and complexity, in spite of their 

 minuteness and the comparative simplicity of the "unicellular" 

 organisms within which they grow; and these complex conforma- 

 tions have a wonderful and unusual appearance of geometric 

 regularity. All these general considerations seem such as to prepare 

 us for some physical hypothesis of causation. The Httle skeletons 

 remind us of such things as snow-crystals (themselves almost endless 

 in their diversity), rather than of a collection of animals, constructed 

 in accordance with functional needs and distributed in accordance 

 with their fitness for particular situations. Nevertheless, great 

 efforts have been made to attach "a biological meaning" to these 

 elaborate structures, and "to justify the hope that in time their 

 utilitarian character will be more completely recognised*." 



As Ernst Haeckel described and figured many hundred "species" 

 of radiolarian skeletons, so have the physicists depicted snow- 

 crystals in several thousand different forms |. These owe their 

 multitudinous variety to symmetrical repetitions of qne simple 

 crystalline form — a beautiful illustration of Plato's One among the 

 Many, to ev napa ra iroXXd. On the other hand, the radiolarian 

 skeleton rings its endless changes on combinations of certain facets, 

 corners and edges within a filmy and bubbly mass. The broad 

 difference between the two is very plain and instructive. 



Kepler studied the snowflake with care and insight, though he 

 said that to care for such a trifle was like Socrates measuring the 

 hop of a flea. The first drawings I know are by Dominic Cassini; 

 and if that great astronomer was content with them they shew how 

 the physical sciences lagged behind astronomy. They date from the 

 time when Maraldi, Cassini's nephew, was studying the bee's cell; 



* Cf. Gamble, Radiolaria (Lankester's Treatise on Zoology), i, p. 131, 1909. 

 Cf. also papers by V. Hacker, in Jen. Zeitschr. xxxix, p. 581, 1905; Z. f. vnss. 

 Zool. Lxxxiii, p. 336, 1905; Arch. f. Protistenkunde, ix, p. 139, 1907; etc. 



I See above, p. 411; and see (besides the works quoted there) Kepler, De nive 

 sexangula (1611), Opera, ed. Fritsch, vii, pp. 715-730; Erasmus Bartholin, De 

 figura nivis, Diss., Hafniae, 1661; Dom. Cassini, Obs. de la figure de la neige 

 (Abstr.), Mem. Acad. R. des Sciences (1666-1699), x, 1730; J. C. Wilcke, Om de 

 naturliga sno-figurers, K. V. Akad. Handl. xxii, 1761. 



