TABLE 2.

Summary of treatments given to solutions of pure Ascaris suum eggs^a

Treatment and step	Reagent			Procedureb
	All steps	Hydrophilic extraction (reagent 1)	Lipophilic extraction (reagent 2)	All steps	Minimum exposurec	Maximum exposured
Flotation
1  2  3	ZnSO4 MgSO4 NaCl			Add 30 ml of reagent, and mix thoroughly. Centrifuge and pour off supernatant into 200-ml centrifuge bottle. Add 170 ml of distilled water. Settle overnight. Aspirate supernatant, and transfer sediment to 15-ml tube. Centrifuge, and aspirate to 1.5 ml. Add 13.5 ml of 0.1 N H2SO4. Centrifuge, and aspirate to 3 ml.
Extraction
4  5  6, 7  8, 9  10, 11		None Acid-alcohol Acid-alcohol Acid-alcohol Acetoacetic buffer	Diethyl ether None Diethyl ether Diethyl ether		Add 4.5 ml of reagent 1 and 3 ml of reagent 2. Shake vigorously for 2 min. Centrifuge and aspirate to 1.5 ml. Add 13.5 ml of 0.1 N H2SO4. Centrifuge and aspirate to 1.5 ml. Add 13.5 ml of 0.1 N H2SO4. Centrifuge and aspirate to 3 ml.	Add 4.5 ml of reagent 1 and 3 ml of reagent 2. Shake vigorously for 2 min. Let sample sit for 30 min. Centrifuge and aspirate to 1.5 ml. Add 1.5 ml of 0.1 N H2SO4.
Incubation  12  13  14	Distilled water 0.1 N H2SO4 0.5% formalin			Add 13.5 ml of reagent. Centrifuge and aspirate to 3 ml.

^aAfter treatment, all samples were incubated for 4 weeks at 26°C. 

^bInitial samples consisted of eggs suspended in phosphate-buffered saline. Except for the samples treated with distilled water or 0.5% formalin, all samples were incubated in 0.1 N H₂SO₄. All centrifugations were at 1,000 × g for 5 min. The steps in these columns refer to all treatments in the flotation, the extraction, or the incubation. 

^c30-min direct exposure to reagents. Rinsing steps decreased residual ethanol concentration to approximately 2 g/liter during incubation. 

^d1-h direct exposure to reagents. Samples were incubated with an approximate residual ethanol concentration of 102 g/liter.