2 DESIGN IN NATURE 



Atoms and molecules for the most part display a tendency to assume symmetric forms and to dispose them- 

 selves in straight lines or in curves ; the curves forming spheres, circles, and spirals, especially the latter. As a 

 consequence, increase, growth, and development in the inorganic and organic kingdoms proceed in one or other of 

 the directions indicated.^ 



Fii:. 1. — Exquisite crystals of snow as figured 

 by Sooresby. Illustrate straight-line formations. 



§ 2. Straight-Line, Radiating, Concentric and Spiral Formations with Traces of Segmentation. 



What I designate straight-line formations produce bodies bounded by plane surfaces ; the curved formations 

 producing spherical, circular, and spiral structures and modifications thereof. The straight-hne formations are 

 represented by crystals of every form and variety, crystallites, and dendrites ; the latter branching and assuming 



a characteristic tree-hke shape, with, in some cases, a certain amount of 

 segmentation. Crystals are formed by aggregations of atoms and molecules 

 from without ; the additions, for the most part, being made in straight 

 lines, and giving rise to plane surfaces bounded by characteristic angles. 

 Not unfrequently crystals display dendritic, radiating, concentric, and 

 spiral arrangements.'^ 



The curved formations are represented by spheres and modifications 

 of spheres, where the atoms and molecules combine to form bodies having 

 concentric and spiral arrangements ; the additions being made in suc- 

 cessive curved layers. 



Beautiful examples of straight-line formations are seen in the crystals 

 of snow, and of the straighb-hne, radiating, and curved formations in 

 the crystals and conglomerations of hail. In the latter the straight-hne, 

 radiating, and concentric arrangements are all present. Perhaps no better 

 illustration of the extraordinary plasticity and power of nature to assume different 

 shapes and conditions, under slightly altered circumstances, can be given than are 

 afforded by the structure of snow and hail respectively (Figs. 1 and 2). 



Examples of crystals are met with in the organic as well as in the inorganic 

 kingdom. Crystals, as a rule, are symmetrical, and characterised by great beauty of 

 outline. They are endless as regards form, and have for the most part an unvary- 

 ing chemical composition. They occur in the soft snow and in the hardest rocks 

 and metals. They are deposited in the sohds of certain plants, and in the fluids of 

 plants and animals, as witness the crystals of sugar, blood, bile, urine, &c. 



Typical examples of crystals displaying straight-line, dendritic, radiating, con- 

 centric and spiral arrangements, with traces of segmentation, are given at Plates i. 

 and ii. From a careful examination of the figures in the plates in question it will 

 be seen that crystals assume a very great variety of form ; the peculiar shape 

 depending, in man}'^ cases, on the condition, for the time being, of the mother hquid 

 as regards temperature, degree of viscosity, and what may be regarded as ad- 

 ventitious circumstances. In other words, crystals, while having a definite 

 chemical composition, and, as a rule, a distinctive form, nevertheless lend them- 

 selves to constructive processes, and admit of modification in accordance with certain 



When so modified they bear the most extraordinary resemblances to certain plants and animals and parts 

 i. and ii. with Plates iii., iv., v.), and support the beUef that the law of increase and 



and that one design runs through the in- 



Fk;. 2. — Various forms of hail as 

 figured by AVhitney. A, hailstone 

 which fell at Bonn in 1822, having a 

 diameter of an inch and a half, and 

 weighing 300 grains. B, sections of 

 differently shaped hailstones, showing 

 a radiating nucleus and concentric 

 layers. C, section of hailstone with 

 minute ciystallic pyramids on its sur- 

 face displaying a radiating arrange- 

 ment. D, the erystallic pyramids 

 detached. 



laws. 



thereof (compare Plates 



growth applies equally to crystals and to plants and animals ; 



^ I desire to point out that I employ the terms atom and molecule in their generally accepted sense, without prejudice, and with the 

 knowledge that some advanced physicists of late years regard the atom as highly divisible. The divisibility of tlie atom does not affect my argu- 

 ment as developed in the present work, and I keep an open mind on the subject. It only pushes the division of matter to a further point. It 

 does not jeopardise the existence of matter or the forces which inhere in matter as such : matter and force to the physicist and physiologist are 

 still realities. They are, as hitherto, indestructible and iixed quantities in the universe. The more minute division of matter is one of detail 

 j'ather than of principle, and is discussed further on (page 180 : The visible and invisible worlds ; new theory of matter, &c.). 



^ In making these general statements I am aware that crystallisation is a complicated process, and results from various and diverse con- 

 ditions. Herr 0. Lehman {Zeitschrift fur KrystallograpMe wiul Mineralogie, von P. Groth, vol. i., 1877) traces crystallisation (1) to the evaiio- 

 ration of a solution ; (2) to the action of chemical re-agents ; (3) to the solidification of melted masses ; (4) to the condensation of vapours ; (5) to 

 change of iixed, physical, isometi'ic modification ; and (6) to separation by electrolysis. 



Crystals have been divided by Webster into (1) the isometric, which have the axes all equal, as in the cube, octahedron, &c. ; (2) the tetragonal 

 which have a varying vertical axis, while the lateral are equal, as in the right square prism ; (3) the orthorliomhic, which have the three axes 

 unequal, as in tlie rectangular and rhombic piisms ; (4) the monodinic, which have one of the intersections oblique, as in the oblique rhombic 

 ])nsm ; (5) the Iriclinic, which have all the three intersections oblique, as in the oblique rhomboidal prism ; and (6) the he:i" (gonal , which have 

 three equal lateral axes, and a yertieal axis of variable length, as in the hexagonal prism and rhombohedron. 



