38 THE AQUAVIVAKIUM. 



I. VERTEBRATE ANIMALS. 



1. Amphibia. 



The Frog, the Toad, and the Newt, belong to 

 the class of animals called Batrachians ; they 

 are also called Amphibia, because they lead a part 

 of their lives breathing in water and another part 

 breathing in air. The frogs and toads, when their 

 aquatic respiration ceases, come out of the water, 

 and live on the land ; but the newts, after this 

 period of their existence is over, still continue 

 to live in the water. Thus, frogs and toads 

 can only be made to inhabit the Aquavivarium 

 during the period that they possess gills, and 

 breathe in water. In this stage of their growth 

 they are called tadpoles, and very interesting 

 fellows will they be found. The tadpoles of newts, 

 frogs, and toads, are very much alike in the early 

 stage of their existence. The spawn of these crea- 

 tures may be obtained from any pond or ditch in 

 the early spring. It consists of a transparent 

 gelatinous mass, in which are imbedded a number 

 of dark spherical masses. These black masses 

 increase in size, and at last burst forth from 

 their parent jelly as little creatures, all head and 

 tail. It is interesting to watch the changes they 

 undergo. First the gills appear, and offer a beauti- 

 ful object under the microscope, as the blood comes 

 through them in the process of aeration ; then the 

 legs make their appearance, and as they grow, the 

 gills become less, and the tail shrivels away ; at 

 last, the young frog or toad is ready to emerge 

 from its nursery in the water ; if kept after this in 

 the Aquavivarium, he dies. Not so with the newts ; 



