94 HAECKEL 



cesses, that keep the body neatly balanced ; when 

 they are no longer required, they sink back into 

 the gelatinous mass. We study the "histology" 

 of these curious social-living creatures under a 

 powerful microscope. As I have explained, the 

 tissues and organs of the higher animals break 

 up under the microscope into a most ingeniously 

 constructed network of tiny living gelatinous 

 corpuscles with a nucleus in the centre — the cells. 

 But our radiolarian has no more got tissues 

 composed of cells than it has stomach or lungs 

 or any other organ. It is merely a single cell 

 with a nucleus and a jelly-like body. Yet in 

 this case the single cell is a whole individual, 

 a complete animal, that lives, moves, eats, 

 breathes, and so on. The radiolarian is, in com- 

 parison with the splendid cell-tapestry of the 

 higher animals, a poor little atom of life. It 

 must be put deep down in the animal series. 

 What a vast distance ! Above is man, built of 

 myriads of cells woven into the most ingenious 

 tissues and the most perfect organs for each 

 function of life ; below we have the radiolarian, 

 in which a single cell must discharge all the 

 vital functions, because its whole body is merely 

 one cell. But there is another wonder. This 

 tiny particle of living slime, floating in the blue 

 waves at Messina, hardly more visible than a 

 drop of spittle, has a most remarkable quality. 

 It is able to assimilate a kind of matter that 

 the chemist calls silicious (flinty) matter — the 

 stuff that forms, when it is crystallised in chemical 



