Jj, Killing, Fixing, and Storing Plant Tissues 



One of the most critical operations in the processing of tissues 

 is the kilhng of the protoplasm. The stopping of life processes within 

 the cells should be accomplished with the minimum structural dis- 

 turbance within the cells and minimum distortion of the arrangement 

 of cells in the tissues. In addition to killing the j^rotojjlasm, the 

 killing fluid or the subsecjuenl processing nuist retain or fix the 

 undistorted structure and render the mass of material firm enough 

 to withstand the necessary handling. 



No single substance has been found to meet the recjuirements of 

 successful jireservation. The formulas used for this pmpose consist 

 of ingredients in such proportions that there is a balance between the 

 respective shrinking and swelling actions of the ingredients. The 

 numerous formulas found in the literature are variations of a com- 

 paratively few fundamental formulas, and the chemical sidxstances in 

 the formulas are few in luunber. Any formula shoidd be regarded 

 as a starling point for experiments to determine the proper balance 

 of ingredients for sjK'cific subjects. 1 he formulas reconnnendrd in 

 this chajiter ha\e been lound to i)e satisfactory for a di\ersit\ ol 

 subjects. 



Preparation of Stock Solutions and Killing Formulas 



The followin" reauents and stock solutions are used in a wide 

 range of killing (fixing) formulas: 



Glacial acetic a(i(l. 



1% acetic acid (a])pr().\iinatcly) , made In adding 10 ct. ol glacial acrlit 

 acid to 990 cc. of water. 



10% acetic acid, made on ihc same basis as ilic above. 

 Propionic acid ma\ he sul)sliuile(l for acetic acid in the al)o\e. 

 \% chromic a( id. (10 g. cliromic anhvchide crystals per liter.) 

 Formalin, the trade name used lor an ac]ueous soliiiioii ol loinialdi Indc. 



(ontainint; '^7 to lO'/r lornialdehyde i;as hv weight. 



I 12 1 



