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UNIT AND DIVISION OF LABOR 



d. The Development of Tissues and Organs 



Observations. 1. We have previously learned that cells 

 doing the same sort of work are said to form tissues, such as 

 muscle tissue, nerve tissue, protecting tissue, etc. How many 



FIG. 46. Different sorts of cells ; some results of division of labor. 



tissues in agastrula? What are they? Note. A tissue is a 

 set of similar cells for a special purpose. 



2. Examine Figure 46 or slides showing different kinds of 

 cells, such as of muscle, nerve, bone, etc. Are they formed for 

 the same or different functions ? See also Figure 9. 



3. What tissues have you noted in a hydra ? 



4. Name some tissues that are likely in your hand. Note. 

 Organs are special sets of tissues, each for a special purpose, 

 as the hand, the eye, the ear, the stomach, etc. 



Conclusions. 1. If organs are made of tissues and tissues 

 of cells, what is your conclusion ? 



2. What is the purpose of different sorts of cells in the 

 'body? 



