IX] OF THE RADIOLARIAN SKELETON 697 



variants of a single type, all related but no two the same, vastly 

 increases our pleasure and admiration. Such is the pecuHar beauty 

 which a Japanese artist sees in a bed of rushes or a clump of 

 bamboos, especially when the wind's ablowing; and such (as we 

 saw before) is the phase-beauty of a flowering spray when it shews 

 every gradation from opening bud to fading flower. 



The snow-crystal is further complicated, and its beauty is notably 

 enhanced, by minute occluded bubbles of air or drops of water, whose 

 symmetrical form and arrangement are very curious and not always 

 easy to explain*. Lastly, we are apt to see our snow^-crystals after 

 a slight thaw has rounded their sharp edges, and has heightened 

 their beauty by softening their contours. 



In the majority of cases, the skeleton of the Radiolaria is com- 

 posed, like that of so many sponges, of silica; in one large family, 

 the Acantharia, and perhaps in some others, it is made of a very 

 unusual constituent, namely strontium sulphate f. There is no 

 important morphological character in which the shells made of these 

 two constituents differ from one another; and in no case can the 

 chemical properties of these inorganic materials be said to influence 

 the form of the complex skeleton or shell, save only in this general 

 way that, by their hardness, toughness and rigidity, they give rise 

 to a fabric more slender and delicate than we find among calcareous 

 organisms. 



A shght exception to this rule is found in the presence of true 

 crystals, which occur within the central capsules of certain Radio- 

 laria, for instance the genus Collos'phaera%. Johannes Miiller 

 (whose knowledge and insight never fail to astonish us§) remarked 



* We may find some suggestive analogies to these occlusions in Emil Hatschek's 

 paper, Gestalt und Orientirung von Gasblasen in Gelen, Kolloid. Ztschr. xx, pp. 

 226-234, 1914. 



t Biitschli, Ueber die chemische Natur der Skeletsubstanz der Acantharia, 

 Zool. Anz. XXX, p. 784, 1906. 



I For figures of these crystals see Brandt, F. n. Fl. d. Golfes von Neapel, xiii, 

 Radiolaria, 1885, pi. v. Cf. Johannes Miiller, Ueber die Thalassicollen, etc., Abh. K. 

 Akad. Wiss. Berlin, 1858. 



§ It is interesting to think of the lesser discoveries or inventions, due to men 

 famous for greater things. Johannes Miiller first used th^e tow-net, and Edward 

 Forbes first borrowed the oyster-man's dredge. When we watch a living polyp 

 under the microscope in its tiny aquarium of a glass-cell, we are doing what John 

 Goodsir was the first to do; and the microtome itself was the invention of that 

 best of laboratory-servants, "old Stirling," Goodsir's right-hand man. 



