The Preparation of Whole Mounts and Smears 101 



Exhausting the aii' Irom the submerged specimens with an aspir- 

 ator aids penetration. li the materials can withstand briel boiling in 

 the fluid on a water bath, penetration and fixation of the color are 

 hastened. Materials preserved in this formula can be subsequently 

 embedded and sectioned, provided that the pieces are small enough 

 to insure quick penetration of the preservative and satisfactory preser- 

 vation of cellular details. 



Keefe's formula is one of the best and shcnild be used if the 

 expensive vnanium salt is available. 



50% alcohol 90 cc. 



Formaldehyde (U.S. P.) 5 cc. 



Glycerin 2.5 cc. 



Glacial acetic acid 2.5 cc. 



Copper chloride 10 g- 



Uranium nitrate 1-5 g. 



Delicate subjects may be ready to use in 48 hr., but most materials 

 require 3 to 10 days for complete fixation of the color. Leafy plants 

 can be treated and then mounted as herbarium specimens, in which 

 the color will persist for many months. This formula does not pre- 

 serve the colors of flowers, nor is it satisfactory for gymnosperms. 



The red and yellow coloration of fruits can be preserved in the 

 following formula (Hessler) : 



Water 1 1. 



Zinc chloride (dissolve in boiling water and filter) . . 50 g. 



Formaldehyde (U.S.P.) '. 25 cc. 



Glycerin 25 cc. 



Allow to settle and decant the clear liquid for use as needed. 



With the introduction of dioxan into microtechnique, several 

 wprkers independently developed the idea of using this reagent in 

 killing and preserving fluids. McWhorter and Weier (1936) , for 

 example, devised the following fornuila: 



Dioxan 50 cc. 



Formalin 6 cc. 



Acetic acid 5 cc. 



Water 50 cc. 



This solution preserves unicellular and filamentous algae, fungi, and 

 other delicate subjects. Temporary mounts for microscopic study can 

 be made on a slide in a drop of this fluid, or permanent slides can 

 be made. 



