33' 



DESIGN IN NATURE 



The 



possess the roots of hfe as witnessed in many of the more highly differentiated and complex organisms 

 potentiahties of life receive in paramecium a new and convincing illustration. 



Every one who studies the movements of paramecium must be struck with their rapidity, grace, and purpose- 

 hke character. It is not possible to regard them as haphazard, reflex, or in any way due to irritability, extraneous 

 stimulation, or elasticity. The paramecium is in no sense an automaton. 



§ 62. Gromia. 



The gromia, like the amoeba and paramecium, is a rudimentary, unicellular, microscopic animal. It belongs to 

 the great group of the Foraminifera, which occurs in incalculable numbers in the ocean, and which has played a most 

 important part in the chalk and hmestone formations of the earth's crust from the earliest times. The Forami- 

 nifera are remarkable for their minuteness, the extraordinary beauty 

 and variety of their shells, and the delicate colours occasionally dis- 

 played by them. Plancus counted as many as 6000 in an ounce of 

 sand from the Adriatic. They are found in milhons on the surface 

 and at the bottom of the sea. In the former situation they form a 

 variously-coloured scum, and in the latter they cover thousands of 

 square miles of the ocean bed with a pinkish-white mud, formed chiefly 

 by their skeletons. The shells of the Foraminifera, as a rule, vary 

 from the yi„ to the ^V of ^^ ^^'^^ i^ diameter. There are, however, 

 genera such as OrbitoUtes which measure ^^ of an inch in diameter. 

 There are also NummuUtes with a diameter of 4^ inches, while the 

 genera Carpenteria and Polytrema measure as much as 5 inches in 

 breadth, and have a thickness of from IJ to 2 inches. 



" The Foraminifera have in past geological times been among the 

 most active agents in building up the sedimentary rock masses of the 

 earth, by secreting the carbonate of lime from the waters of the ocean. 

 This work is still being carried on by them around the shores of 

 continents, where their accumulated shells go to form, along with the 

 land dSris, the terrigenous deposits, and cover large areas of the ocean 

 floor, where, intermixed with coccoliths, they form the well-known 

 Globigerina ooze. 



" The organic rocks formed by the agency of Foraminifera are 

 often of very great thickness and extent, and foraminiferal rocks are 

 found inter-stratified with other deposits in almost every geological 

 formation." ^ 



The most remarkable feature of the Foraminifera is the construc- 

 tion of the shell. This, usually formed of carbonate of Hme, is of 

 every conceivable shape ; varying from the simple sphere and the plain, 

 nearly straight tube to the most exquisitely curved and ornamented 

 spiral. I give selected examples in considerable numbers in another part of the work (Plates xiii. and xiv.). 

 The marvel, and it is a great and significant one, consists in the fact that a rudimentary animal, low down 

 in the scale of being, consisting of a single cell of sarcode with no visible differentiation other than is provided 

 by a nucleus and contractile vesicle, and with no tissues or organs such as nerves, muscles, glands, &c., can, 

 nevertheless, produce the most extraordinarily complicated and elaborate shells known, both as regards the 

 variety of the material employed and the perfection and beauty of design of the finished work. In this we 

 have another and striking example of the potentiality of hving matter. The marvel can only be explained in 

 one of two ways ; either the great First Cause works in and through the apparently simple homogeneous sarcode 

 and directs its atoms and molecules in the direction required ; or the sarcode formed by the atoms and molecules 

 is not simple as is generally believed, but differentiated in a way and to an extent of which we have at present 

 no knowledge and of which we can take no cognisance. This follows, because while the sarcode or substance 

 of each animal is apparently identical, the shells, as stated, vary infinitely as regards general design and detail. 

 They also vary as regards material, being sometimes formed of a membrane, sometimes of a chitinous sub- 

 stance, sometimes of carbonate of lime, and sometimes of sand-grains and adventitious matters such as sponge 



1 "The Fovarainifi'va, being an Introduction to tlie Study oC the Protozoa," hj Frederick Chapman, A.L.S., F.R.M.S., &c. London, 1902. 



Fig. 70. — (/ ivmia ierricola, greatly mugnifisd (after 

 Leidy). Shows an amazing di.splay of sensitive living 

 sarcode streaming and radiating by centrifugal move- 

 ments. The streaming is reversed by centrijietal move- 

 ments. In the whole range of natural history there is 

 no more i-eniarkable example of aggi-essive and re- 

 gressive, vital, purposive movements. The fonvard 

 and backward streaming of gromia greatly resembles 

 similar streaming movements in the plasmodium of 

 the Myeetozoa (Fig. .59). In both cases the move- 

 ments are active, aggressive, and regi-essive spontaneous 

 movements, essentially rhythmic in charaiter. They 

 consi.st of an advancing or centrifugal act (extension in 

 space) and a retreating or ceutiipetal act (retraction in 

 .space). The movements in question are seen in en- 

 dosmose and exosnmse, in tlie formation and disintegra- 

 tion of crystals, in the condensation and rarefaction 

 of nebuhe, in cilia, in hollow and solid muscles, in 

 respiration, alimentation, reproduction, circulation, &c. 



