Smears of gastric extracts or of emulsions of feces, as ordinarily made, generally return partial or unsatisfactory findings. This is apt to be so when specimens are examined with an oil-immersion objective. At the laboratory of gastro-enterology of St. Mary's Hospital (Mayo Clinic) in an effort to make of greater worth the routine microscopic examination of gastric extracts particularly, the procedure described below has recently been adopted.
Advantage is taken of the opportunities offered by agar solutions recently emphasized by Ross.1 These may be combined with anilin dyes and chemicals to suit the work in hand.
—Two per cent. agar solution is made by boiling up an appropriate quantity of best grade strip agar in distilled water. The solution is filtered several times while very hot through double, hydrochloric-acid-washed filter paper. On cooling it solidifies as a firm jelly. It should be fractionally sterilized and refiltered