226 SCIENTIFIC ILLUSTRATIONS [Min 



A Mind in an Atom. 



The mind does not demand a vast theatre as the scene of its 

 operations. Its essential glory is not bound up with vast 

 mechanical movements, but is revealed by the quality of acts. 

 What is more interesting than an examination, by means of a 

 first-rate microscope, of a tiny atom that inhabits almost every 

 clear ditch the Melicerta^ The smallest point which you 

 could make with the finest steel-pen would be too coarse and 

 large to represent its natural dimensions ; yet it inhabits a snug 

 little house of its own construction, which it has built up stone 

 by stone, cementing each with perfect symmetry, and with all 

 the skill of an accomplished mason, as it proceeded. It collects 

 the material for its mortar, and mingles it; it collects the 

 material for its bricks, and moulds them ; and this with pre- 

 cision only equalled by the skill with which it lays them when 

 they are made. As might be supposed with such duties to 

 perform, the little animal is furnished with an apparatus quite 

 unique, a set of machinery to which, if we searched through 

 the whole range of beasts, birds, reptiles, and fishes, and then 

 by way of supplement examined the five hundred thousand 

 species of insects to boot, we should find no parallel. The 

 whole apparatus is exquisitely beautiful. The head of the 

 pellucid and colourless animal unfolds into a broad transparent 

 disc, the edge of which is moulded into four rounded segments, 

 not unlike the flower of the heart's-ease, supposing the fifth 

 petal to be obsolete. The entire margin of this flower-like disc 

 is set with fine vibratile cilia : the current produced runs uni- 

 formly in one direction. Thus there is a strong and rapid set 

 of water round the edge of the disc, following all its irregula- 

 rities of outline, and carrying with it the floating particles of 

 matter, which are drawn into the stream. At every circum- 

 volution of this current, however, as its particles arrive in 

 succession at one particular point, viz., the great depression 

 between the two uppermost petals, a portion of these escape 

 from the revolving direction, and pass off in a line along the 

 summit of the face towards the front, till they merge in a 

 curious little cup-shaped cavity seated on what we may call 

 the chin. This tiny cup is the mould in which the bricks are 



