Fitch & Anders: "Organized Elements" in Chondrites 499 



If aldehydes are reacted with Schiff's reagent, a red- violet color develops that 

 is different from the original fuchsln. In addition to aldehydes, certain ketones, 

 certain unsaturated compounds, and various oxidants can colorize Schiff's 

 reagent.^'* The solution must be fairly freshly prepared; oxidation, aging, 

 exposure to air, and sunlight can recolorize Schiff's reagent stored in the 

 laboratory/ 



In addition to any aldehyde groups present initially, Schiff's reagent will 

 react with any artificially produced aldehyde groups. For example, periodic 

 acid oxidizes 1,2 glycol linkages to aldehyde groups. If one of the hydroxyl 

 groups is substituted with amino alcohol, alkylamino alcohol or carbonyl, it is 

 also oxidized to give a positive reaction. In biological materials, the reaction 

 is relatively specific for carbohydrates, mucoproteins and glycolipids. Un- 

 saturated lipids which can also react are usually removed from biological 

 samples during preparation for microscopical examination.'''^ 



Table 2 

 UV Fluorescence in Orgueil 



In biological tissues the Feulgen reaction is usually considered to be specific 

 for desoxyribonucleic acid (DNA).^'^ As the first step in the procedure, DNA 

 is partially hydrolyzed by 1 n HCl to produce the aldehyde form of desoxyribose 

 phosphate. The aldehyde groups then react with Schiff's reagent to produce 

 the same magenta color found in the PAS reaction. In biological samples, 

 substances which will react directly with Schiff's reagent are usually not 

 present. With meteorite samples it is essential to determine whether or not 

 materials are present that will react directly with Schiff's reagent. Such 

 substances would give a false positive Feulgen reaction and simulate the pres- 

 ence of DNA. To correctly interpret the results of the staining reactions on 

 the meteorite samples, proper controls are necessary. 



To control the staining reactions, sections of rat spleen tissue fixed in Carnoy's 

 solution and embedded in paraffin, as well as samples of kimberlite and Orgueil 

 were studied. Kimberlite, the diamond-bearing rock usually believed to have 

 come from deep within the earth, was chosen becaues it is perhaps more similar 

 to Orgueil in mineral composition than other terrestrial rocks. Both Orgueil 

 and kimberlite consist primarily of serpentine-like hydrated silicates produced 

 from olivine by alteration under aqueous, reducing conditions. For the stain- 

 ing reactions, samples of Orgueil and kimberhte were suspended in 6 per cent 

 gelatin and the mixture was spread on microscope slides and allowed to dry. 



