. Public health laboratory work, including methods employed in bacteriological research, with special reference to the examination of air, water and food contributed . Fig. 56.—The wheat mite (Acarus farin^e). (x 85). its characters are shown in figure 56. The eggs of theparasite are oval. The various fongi which attack corn, are the follow-ing:— I. Oidium ahortifaciens, or ergot, most frequentlyattacks rye (ergot of rye ), and causes when preva-lent in the corn, a condition known as ergotismamong many of those who habitually consume rye X2 308 LABORATORY WORK. bread and biscuits. Those seeds
. Public health laboratory work, including methods employed in bacteriological research, with special reference to the examination of air, water and food contributed . Fig. 56.—The wheat mite (Acarus farin^e). (x 85). its characters are shown in figure 56. The eggs of theparasite are oval. The various fongi which attack corn, are the follow-ing:— I. Oidium ahortifaciens, or ergot, most frequentlyattacks rye (ergot of rye ), and causes when preva-lent in the corn, a condition known as ergotismamong many of those who habitually consume rye X2 308 LABORATORY WORK. bread and biscuits. Those seeds which are not abso-lutely replaced by the fungus are discoloured brown,as is also the flour—which generally has a peculiar sourodour. A microscopic examination shows the charac-teristic appearances seen in figure 57. Chemically, its presence in flour is detected by oneof three methods :— {a) The flour is made into a paste with a weak solu-tion of liquor potassae, and then dilute nitric acidis added to shght excess. When the whole issubsequently neutralised by a little more of the. Fig. 57.—Ergot (after Hassall). (x 250). liquor potassae, a violet-red colour forms if ergotis present, and a violet colour is established whenmore of the alkaline solution is added. [b) On the addition of liquor potassae to the flour, a distinct herring-like odour is appreciable—due topropylamine coming away. (c) The flour is made thoroughly moist with ether, a few drops of dilute sulphuric acid are added,and the whole is then well agitated; on the ad-dition of a few drops of a saturated solution CORN WHEAT FLOUR. 30g of sodium bicarbonate a violet colour appears (Hoffman).2. Uvedo segehim, smut, especially affects barley,rye, and oats. The fine dark dust, which sometimesgives the ear of wheat the appearance of having beenplaced up the chimney, is inodorous, and has suggestedthe popular name dust brand to the made with flour thus affected is bluish. ^oo oo 0° OO O O O CD
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