PROBLEM 118 141 



kinds of cells, such as muscle, nerve, and bone. Why do we have 

 different tissues in a plant or in an animal ? 



NOTE. — The hand is an organ, a structure made up of different tissues, all of 

 which work together for the performance of certain work. 



Name some organ found in an animal; in a plant. Name 

 some tissues that make up your hand ; your foot ; your eye. (Use 

 your Civic Biology, pages 266-271, for this purpose.) 



Conclusion. — 1. Why are cells of different shapes and sizes? 



2. Of what purpose are tissues in our body ? 



3. Why are organs composed of tissues ? Use the term division 

 of labor in writing your answer. 



Problem 117 : To find some of the functions common to all 

 animals. 



Method. — Review the needs of a single-celled animal. What 

 must a single-celled animal do in order to live? 



NOTE. — Remember that food must be obtained, digested, and oxidized to re- 

 lease energy (in a many-celled animal this food must be circulated about the ani- 

 mal). Some of it must be made into living matter, and wastes must be excreted 

 from the body. 



What organs has a single-celled animal that perform each of 

 these functions ? Compare the needs of a paramcecium with our 

 needs. Compare the functions of a paramcecium with our func- 

 tions. Compare, in each, the organs which perform these func- 

 tions so far as you know them. Get assistance from your text- 

 book {Civic Biology, pages 180, 181). 



Conclusion. — How does a single-celled animal compare with a 

 very complex animal in the number of functions and in the organs 

 it has for performing these functions? 



Problem 118' How to know some types of animals in the 

 animal kingdom. 



Materials. — Dried or formalin specimens of sponge, sea 

 anemone, starfish, segmented worms, crustaceans, insects, 

 mollusks, and vertebrates (fish, frog, turtle, bird, and mammal). 



