386 APPENDIX 



iodide in distilled water ; then saturate the solution with 

 metallic iodine. Dilute this with one to three times its 

 bulk of distilled water as desired. Keep all solutions of 

 iodine in the dark. 



21. Magenta. 



Use. — Stains fresh tissues. 



Preparation. — Dissolve one gram of crystallized magenta 

 (roseine) in ninety-nine cubic centimetres of ninety-five 

 per cent, alcohol. Dilute this to any strength needed by 

 adding distilled water. 



22. Mayer^s Pepsin Solution. 



Use. — Culture-medium for yeast, etc. 



PrejJaration. — The following formula is taken from Huxley 

 and Martin's " Practical Biology "•: 



23. Millon''s Reagent. 



Use. — Turns albuminous (proteid) substances red. 



Preparation. — Dissolve metallic mercury in its own weight 

 of strong nitric acid. This is best done by pouring the 

 acid upon the mercury in a beaker. As suffocating 

 fumes and considerable heat are generated, it is best to 

 place the beaker on a cloth under a ventilating hood, or 

 on a ledge outside the window. When the mercury is 

 entirely dissolved add to the solution twice its volume of 

 distilled water. Let the mixture stand for a few hours, 

 then decant it into a glass-stoppered bottle. 



24. Moist Chamber. 



A very simple form of moist chamber in which to ex- 

 amine cultures of spores, pollen-grains, etc., is made in 

 the following manner : From a piece of smooth paste- 



