SH 



DESIGN IN NATURE 



Fig. 63. — JJrosera rotundifolia. Diagi'ani of 

 the same cell of a tentacle, showing the various 

 foi-ms (A, B, C, D, E, F, G, H) siicoessively as- 

 sumed by the aggregated masses of protoplasm 

 (Darwin). 



Mr. (afterwards Mr. Justice) Grove, in his admirable work on the " Correlation of the Physical Forces," thus 

 puts it : " All matter, as far as we can ascertain, is ever in movement, not merely in masses, as with the planetary 

 spheres, but also molecularly, or throughout its most intimate structure. . . . Matter and force are correlates m the 

 strictest sense of the word ; the conception of the existence of the one involves the conception of the existence 

 of the other ; the quantity of matter, again, and the degree of force, involve conceptions of space and time. ... 

 Motion will directly produce heat ; and electricity, being produced by it, wiU produce magnetism— a force which 

 is always developed by electrical currents at right angles to the direction of those currents. . . . Pliicker has recently 

 succeeded in showing that crystalhne bodies are definitely affected by magnetism, and take a position in relation to 

 the lines of magnetic force dependent upon their optical axis or axis of symmetry. . . . The same principles and 

 mode of reasoning might be appHed to the organic as well as the inorganic ; and force, animal and vegetable heat, 

 &c., might, and at some time will, be shown to have similar definite correlations. . . . From Professor Matteucci's 

 experiments it appears that whatever mode of force it be which is propagated along the nervous filaments, this 

 mode of force is definitely affected by currents of electricity." 



From the foregoing it will be evident that motion is a characteristic of all bodies, animate and inanimate. It 

 will therefore occasion no surprise if I lay it down as an axiom that the most rudimentary plants and animals move 

 in all their particles and parts, and that what is true of the lowest plants and animals is equally true of the highest. 



Everything that lives grows and has a hfe history, and the fundamental 

 feature of growth is movement. Movement is essentially of two kinds. 

 There is a movement of the atoms and molecules primarily concerned in 

 growth and development, which, being unseen, is to be regarded as 

 invisible movement, that is, movement not recognisable by the unaided 

 eye ; and there is a movement of plants and animals, and parts thereof, 

 which, being seen, with or without the microscope, may not inaptly be 

 designated visible motion. It is the latter form of motion I propose to 

 discuss here. The difference between visible and invisible motion may 

 be explained as follows. When motion ceases to be visible, that is, when 

 moving masses strike against each other and apparently stand still, motion 

 is re-developed in the shape of heat, which is invisible motion. In the 

 steam-engine, for example, the piston and all its concomitant masses of 

 matter are moved by the molecular dilatation of the vapour of the water, 

 the movement of the molecules being imperceptible. If homogeneous 

 substances come together, heat alone is generated ; but if homogeneous 

 and heterogeneous substances come together, electricity is produced ; and 

 some have thought that, whereas the contents of vegetable cells are 

 heterogeneous, and the saps presented to them are nearly if not quite 

 homogeneous, electricity takes part in the circulation in plants. 

 The microscope becomes a necessity when deaHng with minute masses of living matter such as are met with in 

 protoplasm, cells, tissues, low vegetable and animal forms, &c. 



Darwin has described and figured vegetable protoplasm moving and assuming a great variety of shapes.^ 

 Thus, when speaking of the aggregation of the cell contents of the glands and tenacles of Drosera rotundifolia, he 

 says : " By whatever cause the process may have been excited, it commences within the glands, and then travels 

 down the tentacles. It can be observed much more distinctly in the upper cells of the pedicels than within the 

 glands, as these are somewhat opaque. The httle masses of aggregated matter are of the most diversified shapes, 

 often spherical or oval, sometimes much elongated, or quite irregular, with thread or necklace-Uke or club-formed 

 projections. They consist of thick, apparently viscid matter, which in the exterior tentacles is of a purplish, and 

 in the short discal tentacles of a greenish, colour. These little masses incessantly change their forms and positions, 

 being never at rest. A single mass will often separate into two, which afterwards reimite. Their movements are 

 rather slow, and resemble those of amoebae or of the white corpuscles of the blood. We may, therefore, conclude 

 that they consist of protoplasm. If their shapes are sketched at intervals of a few minutes, they are invariably seen 

 to have undergone great changes of form ; and the same cell has been observed for several hours. Eight rude, 

 though accurate sketches of the same cell, made at intervals of two minutes or three minutes illustrate some 

 of the simpler and commonest changes (Fig. 6-3). 



" The cell A, when first sketched, included two oval masses of purple protoplasm touching each other. These 

 became separate, as shown at B, and then re-united, as at C. After the next interval a very common appearance 



' "Insectivorous Plants," by Charles Darwin, M.A., F.R.S., &(;. London, 1875, pp. 39 to 42. 



® 



Fig. 64. — Drosera rotundifolia. Diagram of 

 the same cell of a tentacle, showing the various 

 forms (1, 2, 3, 4, 6, 6, 7, 8) successively assumed 

 by the aggregated masses of protoplasm (Darwin). 



