CHOLERA. 313 A study of the growth of the organism and the forms which it assumes upon different culture-media soon con- vinces us that we have to do with an organism in no way related to the bacilli. If the conditions of nutrition are U***' >tfV*,fc 3fc>$ >%, i * 'U1 " *VvwwL ' 4 -~%r' FIG. So.—Spirillum of Asiatic cholera, showing the flagella; x looo (Gunther). diminished so that the multiplication of the bacteria by simple division does not progress with the usual rapidity, we find a distinct tendency toward—and in some cases, as upon potato, a luxuriant development of—long spiral threads with numerous windings—unmistakable spirilla. Prankel has found that the exposure of cultures to unusu- ally high temperatures, the addition of small amounts of alcohol to the culture-media, etc., will so vary the growth of the organism as to favor the production of spirals instead of commas. One of the most common of the numerous forms observed is that in which two short curved individuals are so joined as to produce an S-shaped curve. The cholera spirilla are exceedingly active in their movements, and in hanging-drop cultures can be seen to swim about with great rapidity. Not only do the comma-shaped organisms move, but when distinct spirals exist, they, too, move with the rapid rotary motion so common among the spirilla.