l62 



DESIGN IN NATURE 



The collared monad is a minute transparent microscopical creature which lives in fluids and consists of a steni 

 or pedicle by which it is fixed to some foreign object, a pear-shaped body in which can be seen a nucleus several 

 contractile vesicles, food globules. &c. Projecting from the upper part of the body is a long, slender, tapermg, 

 hair-like process k^own as the flagellum. Eising from the upper part of the body rs the beautifully moulded, 



'^t:l2::X^SrL .o..... monad are rts small si.e, transparency, and simple orga^sation 

 ft possesses no alimentary canal, no breathing appara,^, ^ cW^> ^;;o^l^^o nm^es, no ner^, r^ 



reproduces itself perfectly, and in great numbers. It exhibits 

 the potentialities and powers of life in their most rudimentary 

 forms. By feeding the animal on carmine -stained food particles 

 its several parts and its mode of feeding are brought out in 

 strong rehef. The most extraordinary part of the collared 

 monad is its flagellum, a vibratile hair-hke process which is 

 made to sweep round within the egg-cup collar by a great 

 variety of voluntary well-directed movements in such a manner 

 as to produce a succession of currents which cause the food 

 particles floating in the water in which it is immersed to rise 

 up in the vicinity of the monad and flow into the open coflar 

 and downwards in the direction of the body where they are 

 ongulphed. The flagellum is endowed with, practically, a uni- 

 versalitv of motioa, and is thoroughly under control. It is a 

 means to a very obvious end, namely, the securing of food. In 

 it we behold a voluntary instrument of the first importance to 

 the well-being, and even the life, of its possessor. It may be 

 compared to the tongue of the higher animals, composed of a 

 complicated system of muscles ; the fibres of which run in 

 longitudinal, transverse, and obhque directions, symmetrically. 

 The tongue, as is well known, can be made to move in almost 

 every direction. The other important parts of the collared 

 monad are its nucleus and contracting vesicles. The nucleus is 

 a central fundamental structure which plays an important part 

 in reproduction ; usually dividing into two in that process 

 to form two new individuals. The contractile vesicles are re- 

 markable structures from the fact that they are endowed with 

 spontaneous, independent, rhythmic movements which enable 

 them to open and close alternately by centrifugal and centripetal 



Fig. 35. — Collared monad {Monoslga gracilis) fed on 

 eannine ; very greatly magnified. Shows a pear-shaped body 



surmounted by an egg-cup collar. The body terminates in a 

 stem or pedicle which is broken off. d, Collar ; /, flagellum ; 

 '/(, nucleus ; cv, contractile vesicles ; fg, fy, food globules. 



The arrows indicate tlie dii-ection which the food par- 

 ticles, floating in the watei', are obliged to take because of the 

 voluntary well-directed movements of the flagellum (AV. 

 Saville Kent). 



movements with time -regulated beat, after the manner of the 



several compartments of the heart in the higher animals. The 

 contractile vesicles are undoubtedly the harbingers of the heart 

 whenever and wherever they occur. That a creature so rudi- 

 mentary and simple as the collared monad should possess 

 structures which perform such an important rule in the circulation of the higher animals, up to man, may well 

 excite wonder, and that wonder is greatly increased when it is stated that they contain neither muscle nor nerve ; 

 the substances to which we usually refer regulated movements in animals. This marvellous arrangement of life is 

 strangely enough not confined to the monad and other rudimentary animal forms. It first makes its appearance 

 in the plant Volvox glohator, whose water vacuoles open and close rhythmically with the utmost regularity and 

 precision, the vacuoles opening slowly and closing somewhat suddenly as in the ventricles of our own hearts. 



The contractile vesicles of plants and the lowest animals teach a very important lesson, namely, that structure 

 and differentiation, in the ordinary sense, are not necessary to the production of the spontaneous, co-ordinated 

 rhythmic movements on the integrity of which, in ourselves, life depends. They are utterly inexplicable unless 

 we refer them to a First Cause and design. 



The function performed by the contractile vesicles in the collared monad is not quite understood. They 

 are supposed to regulate the amount of fluid in the body for the time being, and to assist in the elimination of 

 effete products. They thus seem to be connected with ingestion and egestion, 



