268 UTILIZATION OF MINUTE LIFE. 



them. In the same way many Infusoria will pro- 

 bably, one day, be classed below Sponges. We 

 must look upon a vast number of these microscopic 

 beings as a group of animals under discussion. 

 Proper places will be assigned to them as we 

 become better acquainted with their organization. 

 In the meanwhile it would be rash to attach too 

 great an importance to the fact of my placing,, in 

 this work, Infusoria before Sponges, and Polypes 

 before Infusoria, when, in a zoological point of 

 view, they might, perhaps, for some years to come, 

 be all jumbled into one chapter. 



I stated in my last chapter, that time was a 

 creation of man. It is equally evident that these 

 zoological divisions are also the work of man, and 

 as Nature knows no time, so also she knows no 

 division. Nature is one harmonious whole, which 

 man has cut up into sections in order to investigate 

 this whole, piece by .piece. One small piece gene- 

 rally suffices for many generations of human 

 intellect ! 



Let us now see, in the fewest words possible, 

 what a sponge is. 



The sponge itself i. e., the substance we use as 

 such is composed of a horny flexible skeleton, 

 forming a dense anastomosed tissue, in which 

 numerous pores are seen. These are the openings 

 of canals which traverse the sponge in all directions. 



