260 PRACTICAL DIRECTIONS CHAT, n 



into four megazooids or into numerous microzooids, and 

 observe their movements when set free. Sketch. 



Euglena. Examine a drop of water containing Euglena 

 with the low power, then cover, and put on the high power. 

 Note 



1 . The spindle-shaped form of the body, and its changes of 

 form in contraction and expansion. 



2. The long flagellum. 



3. The superficial cuticle, and the mouth and conical 

 depression (gullet) 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 " nucleolus," and near the anterior end a non- 

 contractile space into which the gullet and the contractile 

 vacuole open, close to which a red eye-spot is situated. 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 encysted condition, and 

 observe if any of them are undergoing division. Sketch. 



Monads and Bacteria. Examine a drop of water con- 

 taining some putrefying animal or vegetable substance. 

 An infusion of hay is convenient for this purpose : pour 

 boiling water on a handful of hay and strain the fluid through 

 blotting-paper ; shortly afterwards decomposition will 

 set in. 



The first organisms to appear in such a putrefying in- 

 fusion are Bacteria, which are so minute as to appear as 

 mere specks under the high power some of them being 

 only 7> ^ mm. (Y^^jinch) 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. 



