PROBLEM 118 111 



kinds of cells, such as muscle, nerve, and l)one. Why do we have 

 different tissues in a plant or in an animal ? 



Note. — The hand is an organ, a structure made up (jf 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. 



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

 aniinals. 



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 paramoecium with (mr 

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

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

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

 book {Civic Biology, pages 180, 181). 



Conclusion. — How does a single-coll(Ml animal compare with a 

 very complex animal in the number of function.s and in tlie organs 

 it has for performing these functions? 



Problem US' How to know some tyf)es of animcils in the 

 animal kingdom. 



Materials. — Dried or formalin spiM-imens of sponge, se^i 

 anemone, starfish, segnuMited worms, crust a('(>ans, iiiscM'ts, 

 mollusks, and vertebrates (fish, frog, turtle, l)ird, and manunal). 



