42 



EXPERIMENTAL PHYSIOLOGY 



tion to be exposed to the air in a large vessel containing a 

 little water to prevent evaporation. Examine at the end 

 of a few days. What evidence have you that protoplasm 

 requires air? 



(It is the oxygen in the air that the animal uses. This 

 property of taking in air and oxygen is part of a process 

 called respiration.} 



Make a list of all the properties of protoplasm as exhib- 

 ited by the cytoplasm of the amoeba. 



XXV. EPITHELIAL TISSUE (OPTIONAL). 



Apparatus. Prepared slide 1 of cross section of the small intes- 

 tine (human preferred, but rat's or other mammaPs will serve), com- 

 pound microscope. 



Directions Focus 

 with the high power 

 on the cells forming 

 the inner layer of the 

 intestine. Draw six 

 or eight of these cells, 

 showing the large nu- 

 cleus in each, the gen- 

 i4. FIG. 15. eral outline of the 



Epithelial Tissues, a, two forms of epithelial tissue: -,-, -, ,-, j. , ., 



1, columnar; 2 and 3, squamous; c, stratified CeilS ; ancl tJie dlStribU- 



tissue; 6, simple ciliated tissue; d, ciliated col- fton of the protoplasm, 

 umnar tissue. A 



Note the thinness of 

 the cell wall and the absence of intercellular material. 



1 Prepared slides for study of tissues may be bought best of dealers, as 

 their preparation is a matter of delicacy and skill. For those who wish to 

 prepare their own, suitable directions will be found in standard histologies, 

 such as Stohr's or Schafer's, and in Lee's "Vade Mecum." 



