2 ZOOLOGY 



moving organs (the muscles), of threads that convey mes- 

 sages as telegraph wires do (the nerves), and of delicate 

 tubes that convej' air or food to the innermost parts of the 

 body (the air-tubes and the blood-vessels) or carry fluids and 

 particles from the body to the exterior (the excretory and 



Fig. 2. — Ama?ba, the proteus animalcule. Greatly magnified, h., the 

 nucleus ; li'. ',■., water vacuoles ; c. v., contractile vacuoles ;f.v., food vacuoles. 

 E. B. Wilson, " The Cell " 



reproductive ducts). These parts differ in form and arrange- 

 ment in different kinds of animals. The study of the form 

 and arrangement of the different organs of the body is called 

 Anatomy ; the study of the work the jiarts do is called 

 Physiology. 



General Form of the Cricket. — What general resemblance 

 in form is there l^etween a cricket and a cat ? Which end 

 moves forward in locomotion {anterior; the opposite end is 

 called posterior) ? Which surface is next to the earth (ven- 

 tral), and which is normally turned up toward the sky (dor- 

 sal) ? What different structures does each surface bear ? 



