This historic book may have numerous typos and missing text.
Purchasers can usually download a free scanned copy of the original
book (without typos) from the publisher. Not indexed. Not
illustrated. 1921 edition. Excerpt: ...of medium. For quantitative
tests it is still necessary to remove the culture fluid from the
container. Our present me thods leave much to be desired in this
direction; the elaborate devices invented with this end in view by
Wolf and Harris 23 have already been mentioned. For purposes of
following simply the titratable acidity and H+ ion curves the
method used by Randall and Hall 18 is quite satisfactory. ' THE
PRESENT STATUS or THE PROBLEMS OF ANAEROBIC FERMENTATION TESTS The
experiments here outlined suggest the following observations: The
vigorous production of gas by anaerobes is generally to be regarded
as an indication of fermentation. However, two sets of facts may
confuse the utilization of gas as a criterion of fermentation in
special cases; first, the production of gas from simple sugars
present in the medium and not removed by the method of sugar
removal generally employed, i. e., by fermentation with Bact. coli,
and second, the production of small quantities of gas from proteins
by certain organisms, such as B. tetani, not known to have any
action on sugars. The first of these difficulties may be overcome
through the use of B. welchii instead of Bact. coli in the
preparation of sugar-free mediums. The production of carbon dioxide
by B. tetani in both sugar and sugar-free mediums also makes the
utilization of carbon dioxide as a criterion of fermentation
untenable. The utility of titratable acidity as a criterion of
fermentation is limited to mediums not containing coagulable
proteins, the hydrolysis of which by proteolytic organisms greatly
increases the buffer capacity of the titrated samples. An increase
in H ion concentration is regarded as the best evidence of
fermentation. It has the advantage over gas of...
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