REAGENTS AND MOUNTING MEDIA. 485 



Iodine, (Arthur Meyer's). Details of preparation found in footnote to p. 20. 



A special use of iodine is found in Gram's Method of Bacterial Staining. 

 See Gentian-violet and also Corrosive Sublimate. 



Solutions of iodine should be kept in darkness, or else in coloured 

 glass bottles. Or the stock can be kept in a dark cupboard, and 

 that in use replaced at intervals as seems necessary. For very 

 exact purposes iodine solutions should always be kept in the dark. 



See also CJilorzinc iodine. 



green. Watery solution. Use for membrane staining, and as a 

 rapid nuclear stain. 



Acetic. In 1 or 2 per cent, acetic acid, iodine-green is dissolved 

 until the fluid appears a deep blue-green colour. A rapid means of 

 fixing and staining nuclei. 



Iron acetate. | Used in tannin reactions, 71. A dilute 



perchloride solution. > watery solution, to which a drop of 



sulphate solution. ) nitric acid may be added. 



K. 



Knop's Culture Fluid, for fresh water Algae. For preparation and mode of 

 use, see pp. 251-2. 



Lemon, Oil of. Used as a clearing reagent for pollen-grains, 388, 390. 

 Linseed oil. Used for diluting gold -size. 

 Logwood. See Hcematoxylin. 



M. 



Macerating mixture (Schultze's). Several methods for using this important 

 reagent have been suggested. 



(1) Place in a wide test-tube some pieces of chlorate of potash, and 



pour over them sufficient strong nitric acid to completely cover 

 them ; then lay in the fluid longitudinal sections of the material 

 and warm over a flame till gas is actively evolved. Allow it to 

 work for a few minutes, then empty the whole into a dish of 

 water, and carefully wash. Remove the sections with a glass rod 

 into another vessel of water, and thence into water on an object 

 slide ; there they can be torn to pieces with needles. 



(2) Put the sections in a tube with an equal bulk of chlorate of potash, 



cover with concentrated nitric acid, and proceed as above. 



(3) Use 1 gramme chlorate of potash to 50 c.c. nitric acid, and proceed 



as above. 



(4) 3 grains chlorate of potash and 2 drachms nitric acid (sp. gr. I'lO) ; 



keep the sections in this, cold, for a fortnight. 



After carefully washing in alcohol, the preparations as above can be 

 preserved in glycerine. 



