208 SCIENCE FROM AN EASY CHAIR 



to the naked eye is all the more curious and impressive. 

 We have, in fact, parallel organisation and elaboration of 

 structures with special uses, in two absolutely separated 

 grades or strata of living things the one grade marked 

 off by the limitation that only a single cell, a single 

 nucleated corpuscle of protoplasm, is to be the basis and 

 material of elaboration the other and higher grade per- 

 mitting the use of millions of single cells, of endless 

 variety and plasticity, capable of hanging together and 

 being grouped in layers and tissues, in such enormous 

 masses that an elephant or a whale is the result. And 

 we see that the same needs are met, not actually in the 

 same way, but in the same kind of way, in the two cases 

 the food-orifice, the cilia, and the " pulsating vacuole " 

 of the unicellular animalcule do the same services as 

 those done by the structurally different mouth, legs, and 

 kidneys of the elephant. 



