. The principles of bacteriology: a practical manual for students and physicians. ay be seen, but with it degenerated organisms are soconspicuous as to leave no doubt that the so-calledbranching and involution are attributable to the samecause, namely, unsuitable conditions of cultivation. On plain nutrient agar-agar (that is, nutrient agar-agar without glycerin) ; on a medium consisting of driedcommercial albumin dissolved in bouillon (about 10grammes of albumin to 100 of bouillon containing BACILLUS DIPHTHERIJE. 391 1 per cent, of grape-sugar); in bouillon without glycerin,and in bouill
. The principles of bacteriology: a practical manual for students and physicians. ay be seen, but with it degenerated organisms are soconspicuous as to leave no doubt that the so-calledbranching and involution are attributable to the samecause, namely, unsuitable conditions of cultivation. On plain nutrient agar-agar (that is, nutrient agar-agar without glycerin) ; on a medium consisting of driedcommercial albumin dissolved in bouillon (about 10grammes of albumin to 100 of bouillon containing BACILLUS DIPHTHERIJE. 391 1 per cent, of grape-sugar); in bouillon without glycerin,and in bouillon to which a bit of hard-boiled egg hasbeen added, the morphology of the organism is aljout in-termediate, in both size and outline, between the formsseen upon glycerin agar-agar and upon LofBers blood-serum. There will appear about an equal number ofshort segmented and longer, irregularly staining forms;but in general the longest are rarely as long as the longforms seen on blood-serum, and throughout they are notso conspicuous for the irregularity of their staining. Fig. Bacillus dipMheriie. A. Its morphology on glycerin-agar-agar. B. Its mor-phology on Lofflers blood-serum, c. Its morphology on acid blood-serummixture. In cultures made upon two sets of nutrient agar-agartubes, differing only in the fact that one set containsglycerin to the extent of 6 per cent., while the other setcontains none, a noticeable difference in morphology can 392 BAOTEEIOLOGY. usually be made out: while the forms on the glycerin-agar-agar cultures are throughout small, and prettyregular in size, shape, and staining, those on the plainagar-agar are larger, stain less uniformly, vary more inshape, and when stained by Lofi&ers blue are not soregularly marked by pale transverse lines that give tothem the appearance of being made up of numerousshort segments. Though the outline of this organism is more regularunder some circumstances than others, it is neverthelessalways conspicuous for its manifo
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