260 PRACTICAL DIRECTIONS CHAI>. n 



2. The long flagellum. 



3. The superficial cuticle, and the mouth and conical depression 

 (guile f) at the anterior end. 



4. The central part of the body, which contains chlorophyll, except 

 at the two ends. Near the middle is a nucleus enclosing a nucleohis, 

 and near the anterior end a non-contractile space into which a contrac- 

 tile vacuole opens, close to which a red pigment-spot is situated ; the 

 colour of this is due to haematochrome. Grains of paramylum may be 

 recognised near the centre of the body. Sketch before and after 

 staining as above. 



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

 of them are undergoing division. Sketch. 



Monads and Bacteria. Examine a drop of water containing some 

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

 venient for this purpose : pour boiling water 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 ?>57jji 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 flagella (Fig. 70), which, however, like those of 

 Bacteria, can only be seen under a very high power. 



