The Microscope. 67 



Dr. Koch ox the Cholera-Bacillus. — The cholera bacillus 

 is not quite straight, like most other bacilli, but is somewhat 

 ■curved, in the manner of a comma, or even nearly semi-circu- 

 lar. In cultivation there often arises S-shaped figures, and 

 shorter or longer slightly wavy lines. They are endowed with 

 active spontaneous motion. They can be best observed in a 

 a drop of nutrient fluid attached to the cover-glass, which they 

 are seen to swim through in all directions. In gelatine they 

 form colorless colonies, which are at first close and have the 

 appearance of small fragments of glass, but gradually spread 

 through the nutrient fluid. They have a tendency to collect at 

 the margin of the drop, where their peculiar movements can 

 be well-observed, and their comma-like form after treatment 

 with anilin-solution. 



As to the question whether their presence is simply due to 

 the presence of the choleraic disease which promotes their 

 growth and development, or whether they are themselves the 

 cause of cholera, Dr. Koch is very strongly of opinion that the 

 latter is the true explanation, since they are never found either 

 in the organs or the ejecta, except in the case of patients who 

 have either died of or are suffering from cholera. They are 

 also found only in that organ which is the seat of the disease, 

 viz., the intestines. In the first feculent ejecta, the bacilli 

 occur only in small quantities ; while in the later liquid odor- 

 less ejecta, they occur in enormous quantities, all other kinds 

 of bacteria being almost entirely absent; they diminish in 

 number as the excreta become more feculent, and have entirely 

 disappeared when the patient is completely restored to health. 

 Their abundance appears to correspond to the degree of inflam- 

 mation of the mucous membrane of the intestine, attaining 

 their maximum when this is of a bright-red color, and the con- 

 tents a colorless odorless fluid. When the contents become 

 offensive from effusion of blood the bacilli decrease in number 

 and are found only in the vesicular glands and their neigbor- 

 hood. Where death results from a secondary complaint fol- 

 lowing cholera, they are altogether wanting. Their behavior 

 therefore closely resembles that of all other pathogenous bac- 

 teria, their development being proportional to the severity of 

 the disease. — Roy. Mic. Journal. 



