202 



BACTERIA IN RELATION TO PLANT DISEASES. 



Fixing Fluids. 



Absolute Alcohol. 

 Expose 24 hours or more. Very useful for 

 fixing bacteria in tissues, as it prevents their 

 diffusion. It causes, however, considerable 

 shrinkage of the tissues, and the nuclei are often 

 difficult to stain, and are usually distorted. 

 Bacteria fixed in this way stain well in Ziehl's 

 carbol-fuchsin. 



Picric Acid in Hot Absolute Alcohol. 

 CSee p. 8.) 



Mercuric Chloride in Hot Absolute Alcohol. 

 (See p. 8.) 

 Acetic Alcohol ivith Mercuric Chloride. 



Absolute alcohol i 



Glacial acetic acid i 



Chloroform i 



Add mercuric chloride until saturated. \\'ash 

 with alcohol or with alcohol containing tincture 

 of iodine. One of the most rapid fixatives 

 known. 



Acetic Alcohol (Canioy's Fluid.) 



Glacial acetic acid i 



Absolute alcohol 3 



Expose 24 hours or more and wash in alcohol 

 This solution preserves the chromatic and cyto- 



plasmic structures better than alcohol alone, and 

 shrinks the tissues much less. Tissues fixed in 

 this solution take most of the coal-tar stains 

 better also. It has very great penetrating power, 

 which makes it very useful in fixing large pieces 

 of tissue. 

 Chrouio-aceto-osiiiic .Icid (Flcnuniug's Fluids). 



A. Stronger solution — 



1 per cent chromic acid 15 



2 per cent osmic acid 4 



Glacial acetic acid i 



B. \A'eaker solution — • 



I per cent chromic acid 25 



I per cent osmic acid 10 



I per cent acetic acid 10 



Water 55 



Expose 12 to 48 hours and wash m running 

 water. This is probably the most valuable of 

 all the fixing fluids for preserving exactly all the 

 cell structures ; and material fixed in it takes the 

 coal-tar stains unusually well. It has very 

 slight penetration, and therefore the tissues 

 should be cut into pieces not more than 2 milli- 

 meters thick. It should be kept in glass-stop- 

 pered bottles, and should be made fresh every 

 6 months or less. 



For additional formuke consult the various standard text-books, especiallj' Eyre's 

 " Bacteriological Technique," where may be found, among others, the following : 



Kitasato's glucose-formate-bouillon. 

 Iron-bouillon. Lead-bouillon. 



Parietti's bouillon. 

 Carbolized bouillon. 

 Kitasato's glucose-forniate-agar. 

 Guarniari's agar-gelatin. 

 Carbolized agar. 

 Glycerine blood-serum. 

 Heiman's serum-agar. 

 Washbourn's blood-agar. 

 LTrine- gelatin . LTrine-agar. 



Whey-agar. Fish-bouillon. 



Fish-gelatin. Fish-agar. 



Gh'cerinated potato. 

 Glycerine-potato-broth . 

 Eisner's potato-gelatin. 

 Goadby s potato-gelatin . 

 Beer-wort. Wort-gelatin. 



Wort-agar. Wine-must. 

 Gasperini's wheat-broth. 

 Bread-paste. Milk-rice. 



Pakes' iron-peptone-solution. 

 MacConkey's bile-salt-broth. 

 MacConkey's bile-salt-agar. 

 Sabouraud's French proof agar. 

 Blaxall's English proof agar. 



