128 METHODS IN PLANT HISTOLOGY 



solution immediately before using. Do not make the solution stronger 

 than 1 per cent; usually 0.2 per cent is strong enough. Dr. Land does 

 not measure, but simply adds enough dichromate crystals to make the 

 water pale yellow. 



Smear a few drops of the 1 per cent solution of gum arable on the 

 slide; flood with the dichromate solution; warm to straighten the rib- 

 bons; drain off the excess water and let the preparation dry in the 

 light. The exposure to light renders the gum insoluble in water. 

 LePage's glue or Mayer's albumen fixative may be used instead of 

 gum arable. 



The foregoing directions are taken from Dr. Land's notes. 



With the ordinary Mayer's albumen fixative, the dichromate of 

 potash, without the gum arable, may be used in floating out ribbons, 

 and makes a stronger fixative than the Mayer's formula. 



Szombathy's fixative. — 



Gelatin 1 g- 



Distilled water 100 c.c. 



Salicylate of soda (a 2 per cent solution) 1 c.c. 



Pure glycerin 15 c.c. 



Dissolve the gelatin in water at 30° C, add the salicylate of soda, 

 shake well, cool, and filter through cheesecloth; then add the 15 c.c. 

 of glycerin. The solution should be perfectly clear. 



A couple of drops of the fixative, with a couple of drops of 2 per cent 

 formalin, is rubbed on the sHde. The sections are then added, and 

 straightened out. The formalin makes the gelatin insoluble. The fixa- 

 tive is much like Land's and is used for difficult material which is not 

 held by Mayer's fixative. 



Haupt's fixative. — 



Gelatin 1 g. 



Phenol crystals 2. g 



Glycerin 15 c.c. 



Distilled water 100 c.c. 



This is a modification of Szombathy's formula. The gelatin is dis- 

 solved at 30° C. Gelatin which will not dissolve at this temperature is 

 not satisfactory. 



Place a small drop of the fixative on the slide and smear with the 

 finger until the film is very thin. Flood the slide with a 2 per cent solu- 

 tion of formalin in distilled water, put on the ribbon, warm it, and 

 proceed in the usual way. 



