2 g ELEMENTARY ZOOLOGY. 



will make satisfactory crystals if treated in this way: 

 common salt, alum, sodium carbonate, blue vitriol. Ex- 

 amine the smaller crystals with a lens or microscope. 

 Draw a few of the simpler crystal forms. 



Enumerate your observed characteristics in such a 

 way that your statements will be true of all your crystals 

 and not merely of some selected crystal. Does your list 

 describe the crystals in such a way that a newcomer 

 would understand from it alone what you have been 

 studying? 



Of the characters mentioned, which seem to you most 

 distinctive; that is, which seem to make the crystal a 

 crystal? If you were to break a crystal would you have 

 a number of small crystals? Why? How would you 

 name the quality which makes this true? 



d. Shells. Use as many different kinds of shells as 

 you can get conveniently. Study as above. What 

 qualities are common to all the shells? Draw one or 

 two figures of shells. Which characteristics make them 

 shells? Which are incidental qualities; that is, so 

 variable as not to affect the "shell-ness" of the shells? 



Do not mix observations and inferences. 



e. Plants. Note the characteristics of plants in the 

 same way. 



In this exercise it is legitimate to use all kinds of plants 

 that you are familiar with, whether you actually have 

 the specimens in the laboratory or not : as trees, shrubs, 

 herbs. 



The teacher should also supply some specimens of 

 mosses, of mushrooms and toadstools (fungi), and some 

 of the green felt-like plants (algce) that grow in water. 



Is there anything you can actually observe that is 

 common to all of these? You cannot directly observe 



