26o PRACTICAL DIRECTIONS CH. Ii 



5. Look for specimens in the resting condition, and observe if any 

 of them are undergoing division. Sketch. 



Bacteria and Monads. Examine a drop of water containing some 

 putrefying animal or vegetable substance. An infusion of hay is con- 

 venient for this purpose : — pour boiling vifater on a handful of hay and 

 strain the fluid through blotting-paper ; shortly afterwards decom- 

 position will set in. 



The first organisms to appear in such a putrefying infusion are Bacteria, 

 which are so minute as to appear as mere specks under the high power 

 — some of them being only ^^ mm. (T^iirir inch) in length, or even 

 less. Careful examination will show globular, rod-like, and spiral 

 forms, all capable of movement at one phase of their existence. Monads 

 will appear somewhat later, and may be recognised by their ovoidal 

 form and their two flagella, which, however, like those of bacteria, can 

 only be seen under a very high power. 



