28 LABORATORY METHODS otf 



3. Examine, note the manner of motion and sketch 

 the animal in several positions. 



THE CEXL WAU,. 



The cell wall is a delicate membrane surrounding 

 the cell-body, and is derived from the cell-body. 



Exercise No. 15. Make a microscopic preparation of 

 Protococcus and observe the cell wall. 



The Nucleus: This is the highly refractive body 

 found in the cell-body, and is composed of the nuclear 

 membrane, nuclear network and nucleolus, seen only 

 under very H. P. This can be seen in the protococ- 

 cus preparation. 



Centrosomes : These are highly refractive bodies 

 seen in the nucleus, and they preside over the repro- 

 duction of cells, while the nucleus transmits the hered- 

 itary traits of the parent cell to the new one. Leroy. 



The properties of a cell are motion, reproduction, 

 metabolism, growth, irritability and function. Metab- 

 olism is that property of a cell by which it takes in 

 nutriment and assimilates the same, and the property 

 of excreting the waste matter, which is the result of 

 metabolism. Irritability is the property of a cell 

 to respond to nervous stimulation. The function of 

 a cell is the work the cell will do. Reproduction of a 



