INTRODUCTION 



FIG. 3. Various Forms of Cells. 



in the fairy tale. We can use this energy to produce light, 

 heat, or electricity, or to do work. 



In other words, energy, originally derived from the sun, 

 was stored up in the coal and hidden for countless years 

 until changed by burning into the energy of heat, move- 

 ment, light, and electricity. 



So it is with the warm, living, wet protoplasm of our 

 bodies, in the presence of oxygen. It is ever being burnt 

 or broken up into simpler 

 compounds. The energy 

 thus released may show 

 itself as heat or motion. 

 It is for this reason that 

 our bodies are warm and 



, , . A, columnar cells found lining various parts 



that we nave tne power of the i nte stines (called columnar efithe- 

 of movement. Hum); S, cells of a fusiform or spindle 



shape found in the loose tissue under the 

 skin and in other parts (called connective- 



Experiment i . To examine tissue cells} . c ^ cell having many processes 



a typical nucleated cell. A or projections such are found in some 



colorless human blood corpus- kinds of connective tissue; D, primitive 



cle is a typical nucleated cell. cells composed of protoplasm with nucleus, 



J and having no cell wall. All are repre- 



Wind a piece of twine tightly sented about 400 times their real size . 



around the last joint of a finger. 



Prick the skin with a clean needle. A drop of blood will flow. Dilute 

 it with a drop of water, or still better, with a few drops of very dilute 

 acetic acid. Spread the diluted blood on a piece of glass and put 

 under a cover glass. Examine with a compound microscope. 



A large number of red corpuscles may be seen and with some 

 patience one or more colorless cells. An internal rounded body in 

 the colorless cells may become visible, which is the nucleus! 



1 Place a drop of carmine fluid on the slide close to the edge of the 

 cover glass and press a piece of blotting paper against the opposite edge 

 to absorb a little of the liquid. When the blood under the microscope 

 is thus stained with carmine fluid, the nucleus is generally more deeply 

 stained than the rest of the corpuscle. 



