CHAPTER XXXVI. 531 



by the insertion of cigarette paper between slide and cover -glass. So 

 long as water remains in the vessel attached to the arm, the linen and 

 the fluid under the cover will remain moist. For many purposes the 

 live slide devised by Botterill and described in The Microscope and its 

 Revelations by DALLINGER, p. 340, will be found extremely useful. 



999. General Morphology. Here great attention must be paid to 

 modern cytologic methods. The most perfect fixing and staining 

 technique should be used in any detailed study of the protozoa, and yet 

 this is seldom found. Methods of fixation will necessarily differ 

 according to whether one wishes to study nucleus, cytoplasm or 

 such cytoplasmic inclusions as mitochondria or Golgi apparatus. 

 Different methods are also frequently necessary according to the 

 organisms studied. For purposes of convenience it is proposed to 

 treat the fixing and staining of protozoa under the following head- 

 ings : Amoeba, Coccidia, Ciliata, Flagellata, Hcemamcebce. 



1000. Amoebae. For temporary purposes many amoebae may be 

 stained and fixed by running a drop of 1 per cent, chromic acid 

 under the cover-glass and then running in a little alum carmine 

 followed by water. Staining intra vitam is very conveniently 

 carried out by means of an agar jelly. A 2 per cent, solution of 

 agar in distilled water is made ; this is cleared with egg white and 

 filtered hot and distributed in 5 c.c. quantities in test tubes. For 

 use a tube is melted by steeping in boiling water in a beaker and a 

 few drops of the selected stain is added and well mixed. A little of 

 the molten agar is then poured on to a slide and allowed to set. 

 The amoebse are distributed in a drop of fluid on a cover-glass, which 

 is then inverted on the jelly. The preparation is at once examined 

 with the microscope. Staining takes place progressively till the 

 nucleus is tinted, when " death " occurs. One of the best stains 

 for such a method is Unna's polychrome methylene blue. For 

 permanent preparations one of the most satisfactory methods is 

 that used by the writer. Slides are coated with a very thin film of 

 molten agar. This is conveniently done by pouring a very small 

 quantity of the agar on one end of a perfectly clean slide and spread- 

 ing it out quickly into a thin film over the slide by means of a warmed 

 glass rod. As soon as the agar has set the slides are stored in a 

 moist chamber till required. A drop or two of the fluid culture 

 containing the amoebae is spread gently over the surface of the agar 

 with either a platinum loop or a glass rod, great care being taken 

 not to break the thin agar film. The slide is then placed film side 

 up in a moist chamber and allowed to remain for from ten minutes 

 to half an hour or more. In this time the amoebse have generally 



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