APPENDIX. 283 



Romanowsky. Staining sections with Romanowsky stains is not very satis- 

 factory. The differential staining seems to fade out in passing through the alco- 

 hols. This may be avoided by blotting the section after staining and differentiation 

 and then applying the xylol to the blotted section. After staining with Giemsa's 

 stain for 10 to 15 minutes, differentiate with i to 500 acetic acid. When the section 

 has a pinkish tinge, wash in water, dry, clear in xylol and mount. 



A very satisfactory Giemsa may be made by taking i gram of methylene blue, 

 1/2 gram of sodium bicarbonate and 100 c.c. of water and polychroming as for King's 

 stain. Remove the dried stain from the porcelain dish and put it into a bottle. 

 Then rinse out the dish with methyl alcohol and pour into the bottle. There should 

 be 100 c.c. for this amount of stain. Let stand 3 to 5 hours, then filter. To the 100 

 c.c. of methyl-alcohol solution add 100 c.c. of glycerin containing 1/2 gram of 

 yellow eosin. 



B MOUNTING AND PRESERVATION OF ANIMAL PARASITES. 



To Mount Small Round Worms. Wash the hook, whip or filarial worm in 

 salt solution, then drop in 70% alcohol containing 5% of glycerin; the glycerin- 

 alcohol mixture being at a temperature of 60 C. When cool, pour into Petri dishes 

 and allow the alcohol to evaporate in the 37 C. incubator. 



Mount in glycerin jelly, preferably in a concave slide, and ring the preparation 

 with gold size. The following is the formula for Kaiser's glycerin jelly: Soak 

 one part of gelatin in 6 parts of distilled water for two hours. Then add 7 parts 

 of glycerin. To the mixture add i% of carbolic acid, warm for 15 minutes, with 

 constant stirring, and then filter through cotton. 



To Prepare Tape-worms. Wash in salt solution. Wrap around a piece of 

 glass as a glass slide and fix in salt solution containing 2 to 5% of formalin. 

 Then keep the preparation permanently in 70% alcohol. If preferred, the specimen 

 may be run through alcohols and xylol and mounted in balsam. 



Larvae. Mosquito larvae may either be prepared as for small round worms 

 or they may be dropped into 70% alcohol at 60 C. and then passed through alcohols 

 and cleared in xylol and mounted in balsam. Flukes and insects may require 

 treatment with hot (60 to 70 C.) solution of 10 to 20% sodium-hydrate solution. 

 Then wash thoroughly in water and subsequently pass through alcohols to xylol 

 and mount in balsam. Clove oil or cedar oil clears more slowly, but makes 

 specimens less brittle than does xylol. Another satisfactory method is to drop 

 insects or larvae into acetone at 60 C. and after being in this from i to 12 hours to 

 clear in xylol or clove oil and mount in balsam. 



Looss has a method of first washing a small nematode or delicate fluke in salt 

 solution. Then pouring this first salt solution out of the test-tube in which the wash- 

 ing was carried out, to add fresh salt solution, and then an equal amount of saturated 

 aqueous solution of bichloride of mercury, The shaking is easily carried on in the 

 test-tube. After washing in water the worm is passed through alcohols, one strength 

 of which should contain iodine. Clear in xylol and mount in balsam. 



