CH. IX] ON CONCRETIONS, SPICULES, ETC. 465 



ways. For instance, Rhumbler has shewn that if a thread of 

 glass be covered with shellac and brought near a drop of 

 chloroform suspended in water, the drop takes in the spicule, 

 robs it of its shellac covering, and then passes it out again*. 

 It is all a question of relative surface-energies, leading to different 

 degrees of "adhesion" between the chloroform and the glass or 

 its covering. Thus it is that the Amoeba takes in the diatom, 

 dissolves off its proteid covering, and casts out the shell. 



Furthermore, as the whole phenomenon depends on a distribu- 

 tion of surface-energy, the amount of which is specific to certain 

 particular substances in contact with one another, we have no 

 difficulty in understanding the selective action, which is very often 

 a conspicuous feature in the phenomenon f. Just as some caddis- 

 worms make their houses of twigs, and others of shells and again 

 others of stones, so some Rhizopods construct their agglutinated 

 "test" out of stray sponge-spicules, or frustules of diatoms, or 

 again of tiny mud particles or of larger grains of sand. In all 

 these cases, we have apparently to deal with differences in specific 



* Rhumbler, Physikalische Analyse von Lebenserscheinuiigen der Zelle, Arclw 

 f. Entw. Mech. vn, p. 103, 1898. 



■f The whole phenomenon is described by biologists as a "surprising exhibition 

 of constructive and selective activity," and is ascribed, in varying phraseology, to 

 intelligence, skill, purpose, psychical actiArity, or "microscopic mentality": that is 

 to say, to Galen's rex^i-Kr) 0i'>ais, or " artistic creativeness " (cf. Brock's Galen, 1916, 

 p. xxix). Ci. CaTY>en.teT, Mental Physiology, 1874, p. 41; Norman, Architectural 

 achievements of Little Masons, etc., Ann. Mag. Nat. Hist. (5), i, p. 284, 1878; Heron- 

 AUen, Contributions... to the Study of the Forammifera, Phil. Trans. (B), ccvi, 

 pp. 227-279, 1915 ; Theory and Phenomena of Purpose and Intelligence exhibited by 

 the Protozoa, as illustrated by selection and behaviour in the Foraminifera, Journ. R. 

 Microscop. Sac. pp. 547-557, 1915; ibid., pp. 137-140, 1916. Prof. J. A. Thomson 

 (New Statesman, Oct. 23, 1915) describes a certam little foraminifer, whose proto- 

 plasmic body is overlaid by a crust of sponge-spicules, as "a psycho-physical 

 individuality whose experiments in self-expression include a masterly treatment of 

 sponge-spicides, and illustrate that organic skill which came before the dawn of Art." 

 Sir Ray Lankester finds it "not difficult to conceive of the existence of a mechanism 

 in the protoplasm of the Protozoa which selects and rejects building-material, and 

 determines the shapes of the structures built, comparable to that mechanism which 

 is assumed to exist in the nervous system of insects and other animals which 

 'automatically' go through wonderfully elaborate series of complicated actions." 

 And he agrees with "Darwin and others [who] have attributed the building up of 

 these inherited mechanisms to the age-long action of Natural Selection, and the 

 survival of those individuals possessing quaUties or 'tricks' of life-saving value," 

 J. R. Microsc. Soc. April, 1916, p. 136. 



T. a. 30 



