456 ZOOLOGY. 



organs of the dogfish, the earthworm, and the pond mussel. 

 Give a brief account of the chemical constituents, structure, 

 and functions of the blood in each case. 



8. Give an account (with diagrams) of the lowest and 

 highest degrees of structure known to you in the Protozoa. 

 How do unicellular animals differ from unicellular plants ? 



9. (a) Describe from without inwards the structures 

 visible in a transverse section of a Hydra ; (b) describe 

 similarly a transverse section of an earthworm taken about 

 the fortieth segment. In both cases describe the tissues 

 present and the characters of the cells which form them, 

 (c) State what is the most important structural difference 

 between Hydra and the earthworm as shown by these two 

 sections. 



10. In what essential respects does the structure of Hydra 

 differ from that of Paramecium? Describe the methods 

 of reproduction in each of these animals. 



11. Describe the reproductive processes and the develop- 

 ment of the egg in Hydra, and contrast therewith the 

 modes of reproduction observed in Paramecium and Amoeba. 



12. What substance is excreted by the renal organ of a 

 frog, and what relation does this substance bear to the 

 general life of the organism ? Describe the parts by which 

 similar excretion is believed to be effected in Amoeba, Hydra, 

 earthworm, mussel, and crayfish. 



13. Describe fully (a) the central nervous system, (b) the 

 notochord and its sheath, of Amphioxus. (c) Compare 

 the central nervous system of Amphioxus with the central 

 nervous system of Lumbricus. 



14. What is a gastrula ? With what lower type has the 

 gastrula been compared ? Discuss the comparison. 



15. What is meant by the term serial homology ? Illus- 

 trate your answer by reference to the appendages of Astacus. 



16. Draw diagrams, with the parts named, of the central 

 nervous system and renal organs of (a) Lumbricus, (b) 

 Astacus, and (c) Anodon. (d) Compare Lumbricus and 

 Anodon, in respect of their nervous systems; and (e) Astacus 

 and Anodon, in respect of their renal organs. 



17. Describe the renal excretory and the reproductive 

 organs of the mussel, the earthworm, and the frog. 



