46 GENERAL BIOLOGY. 



II. Resting Bacteria Zooglsea Stage. 



Examine the scum (zodglcea) from the surface of 

 hay or of other infusions, or of aquaria, etc. 

 Observe : 



The multitudes of motionless bacteria im- 

 bedded in a gelatinous substance. 



III. Cover-glass Preparation. 



With the forceps hold a perfectly clean cover-glass 

 nearly horizontal and bring its lower side just 

 into contact with the surface of the liquid con- 

 taining bacteria (the best results are from a 

 scum that is only just visible). Put the cover - 

 glass, wet side uppermost, on a piece of filter- 

 paper slightly inclined in order that the water 

 may drain off. When the cover-glass is dry, 

 pass it quickly three times through a flame y 

 put a drop of methyl violet upon the cover- 

 glass j after three or four minutes rinse off 

 with distilled water; invert the cover-glass 

 upon a drop of water on a slide and examine 

 with a high power. Observe : 

 The deeply stained bacteria. 

 The differences in form and size. 



Sketch a few of each form. 

 IY. Experiments. 



1 . Clean a potato thoroughly, sterilize it in steam 

 for an hour, and cut it lengthwise into halves 

 with a knife sterilized in the flame of 

 a Bunsen burner. Put the halves on a 



