8 



The Order of Dea^elopment in the animal king- 

 dom, is from the lower to the higher. The coils of 

 ascent around a central stem are formed by a system, 

 of dicliotomoiis branches at right angles to each other. 

 The alternating pairs of ))ranches compose one circle 

 of four rays of related animals, with a central stem 

 of hiirher forms. The hiodier stem is analogous to the 

 perpendicular axis of the snow-flake ; to the trunk of 

 a tree ; to the earth's axis of rotation ; to the centre 

 of rotation of the planetary system ; and to ever}' 

 axis of rotation in nature. 



Beyrinninu- with the lowest organisms, the Plastides 

 of Haeckel may be considered as the root of the ani- 

 mal kingdom. These organisms are scarcely, if at all, 

 separable from Plant-Life, and barely removed from 

 the mineral kingdom. From this root diverge four 

 great groups of Protozoans. The first pair of 

 branches are the Polycystines and Sponges, together 

 comprising the Actinozoolds. The Polycystines, among 

 annuals, represent the Diatoms of the vegetable king- 

 dom ; and the Sponges are also analogous to plants. 

 The Diatoms, Polycystines, and some of the Sponges 

 are siliceous, when there are hard parts. Prof. Agassiz 

 went to his grave (loul)ting whether the Sponges 

 should be classed among Plants or Anhnals. These 

 doubts are not generally shared by naturalists, and 

 some consider the Sponges among the more highly 

 organized of Protozoans. 



The next pair of branches are the Rhizopods or 

 Root-footed animalculaj, and the Infusoria. The 

 Rhizopods, in certain external characters, foreshadow 

 the Mollusca, especially the cephalopods. They are 



