SYSTEMATIC AND DESCRIPTIVE. iyi 



The surface exposed to the air exhibits no trace 

 of the bacilli. 



To investigate the tubes microscopically, a steri- 

 lised glass tube with a capillary end may be used, 

 with its neck plugged with sterilized cotton wool, 

 and provided at the mouth with a suction ball. 

 The capillary end is thrust into the cultivation, 

 and a small fragment removed by aspiration. In 

 the course of the first day the bacilli spread 

 throughout a great part of the agar-agar in such 

 a way that a more or less equally diffused cloudi- 

 ness of the medium ensues, with subsequent ap- 

 pearance of strongly marked clouds or lines of 

 turbidity. At the same time gas bubbles develop 

 along the needle track, and a collection of liquid 

 takes place, while spore formation also commences. 

 The following day these appearances are more 

 marked, the opacity is more pronounced, the develop- 

 ment of gas increases, and the liquid contains more 

 spore-forming bacilli and numerous free spores. 



The nutrient gelatine cultures during the first day 

 show no macroscopic change, but after a few days 

 the piece of tissue is surrounded with a white halo. 

 This gradually spreads in all directions, and is ap- 

 parently beset with hairs. The gelatine liquefies, 

 and the fragment of tissue, degenerated bacilli, and 

 spores, sink to the bottom. The cultivation is also 

 very characteristic in -J per cent, nutrient agar-agar. 

 If placed in the incubator, in a few hours a cloudi- 

 ness forms around the piece of embedded tissue, 



