CHAPTER I 



Introductory 



THE large collection of living animals belonging to 

 the Zoological Society v contains at any given 

 time representatives of all the principal families of 

 vertebrated animals, as well as a few invertebrates, 

 such as insects, scorpions, and the like, which latter are 

 harboured in the Insect House. The great wealth of 

 that collection will give some notion of the extreme 

 productiveness of Nature, and will also emphasize the 

 great uniformity which underlies so much superficial 

 diversity. With its wild, that is uncaged, inhabitants 

 the Zoological Gardens represents in a few square yards 

 the animal population of the globe. For all the great 

 groups into which animated nature can be divided have 

 here their representatives. Animals, in fact, fall into 

 only about a dozen main groups or Phyla. At the 

 bottom of the series we have the unicellular organisms, 

 as a rule of minutely microscopic size and rarely visible 

 at all to the naked eye ; these comprise an infinite 

 variety of creatures, called by the earlier investigators 

 Infusoria, since they appeared in infusions of organized 

 matter. There is not a pool or even puddle in the 

 Zoological Gardens which has not its population of 

 Amoebae and many other of these Protozoa. The 

 remaining Phyla are multicellular organisms collectively 

 termed Metazoa. The first group of the Metazoa, that 

 of the Sponges, may perhaps be represented by the fresh- 



Z.G. I B 



