ANTHRAX. 275 



one species or in another, those found in a guinea-pig being 

 thicker than those seen in the mouse or sheep, whilst those 

 in the rabbit are thinner than any of those above mentioned. 



If one or two of these bacilli be placed in a moist cell, in 

 what is called a hanging drop of nutrient broth, and the 

 temperature be kept at about 37 C., the organism may be 

 kept under observation under the microscope during the whole 

 course of its development. First, the short rods so increase 

 in length that they may ultimately cover a whole field of the 

 microscope, the protoplasm at the same time becoming 

 granular ; then a large number of very minute points make 

 their appearance, the hyaline appearance is gradually lost, 

 and the threads become quite opaque. A little later, if the 

 observation be continued, it 'will be found that instead of a 

 single thread, little bundles of the same long threads make 

 their appearance, in which there are found, at pretty regular 

 intervals, the highly refractile bodies with well-defined 

 margins and sheaths which have already been described as 

 spores. When the spores occur in long threads there is 

 usually a slight enlargement at the point at which the spore 

 is situated, and this, with the bright shining point, gives to 

 these spore-bearing threads an appearance that is described 

 as being like a chain of pearls. In many cases the spores 

 make their appearance in the shorter rods. 1 In place of the 

 regular forms above described there are others, or involution 

 forms, which are found to present themselves when the 

 organism is grown under unfavourable conditions ; for ex- 

 ample, irregular moniliform threads are usually met with 

 where the temperature is too high or too low, the soil is 

 exhausted and so on. 



It has been found by Lehmann, Hime, Buchner, Behring, 

 and Roux that anthrax bacilli may be obtained that do not 

 give rise to spores. This appears really to be due to an 

 interference with the vitality of the protoplasm, as asporo- 

 genous organisms are best obtained by acting upon them 

 with antiseptics, be these chemical or physical. Roux, for 

 example, was able to obtain asporogenous bacilli, and bacilli 

 that remained asporogenous for several generations, simply 



1 The development of the spore has already been described, as most of 

 the descriptions of the setting free and development of the spores are taken 

 from observations made on this species and described by Koch, Buchner, 

 Prazmowski and others. 



