CONTENTS 



CHAPTER PAGE 



I. The Unicellular Animals : The Amceba (Amceba, 

 Various Species) ; The Bell Animalcule (Vorti- 



cella) I 



II. The Hydra (Hydra Viridis, Hydra Grisba, Etc.) . 13 



III. The Earthworm (Lumbricus and Allolobophora, 



Various Species) .... 19 



IV. The Crayfish (Astacus Fluviatilis) 30 



V. The Cockroach (Blatta Orientalis) 50 



VI. The Metamorphoses of Insects 57 



VII. The Pond Mussel (Anodonta Cygn^a) .... 61 

 VIII. The Snail (Helix Pomatia, Helix Hortensis, Etc.) 67 

 IX. The Frog (Rana Temporaria and Rana Esculenta) 73 

 X. Skeletal and Integumentary Structures in Verte- 

 brates 85 



XI. The Egg, the Sperm, and the Development of the 



Chick 118 



XII. Morphology of Organs 143 



XIII. The Morphology of Tissues (Histology) .... 167 



XIV. Classification. The Differences between Plants 



and Animals 173 



XV. The Classification of Animals 183 



