29O BACTERIA. 



been proved that the disease may be produced without 

 fail if certain definite precautions are taken before the 

 inoculation be made. One great difficulty connected with 

 the obtaining of pure cultivations was, of course, that 

 under the conditions favourable to the growth of the 

 tetanus organism, other anaerobic bacteria would also 

 take the opportunity of developing. Some only of these 

 other organisms, however, give rise to the formation of 

 spores, and this occurs at a later date than in the case of the 

 tetanus bacillus. Kitasato, very ingeniously, made this fact 

 the stepping-stone to the cultivation of a pure growth of the 

 spore-bearing tetanus bacillus. As we have already seen, 

 spores of many bacteria can readily withstand a high tem- 

 perature (in some cases of even 100 C., if this is not continued 

 for too long a time, and they will withstand for a con- 

 siderable period the action of a temperature of 80 C.), whilst 

 the vegetative or fully developed forms are killed off very 

 rapidly at a comparatively low temperature. Kitasato's 

 method of procedure was as follows : From the immediate 

 neighbourhood of the suppurating wound of a patient who 

 had died from tetanus, he took a small fragment of tissue, 

 and placing it under suitable nutrient conditions, i.e., in the 

 specially prepared gelatine at a temperature of little over 

 30 C., and in an atmosphere of hydrogen, he obtained 

 a very luxuriant growth of anaerobic organisms ; amongst 

 these he observed that the drum-stick-shaped organisms 

 developed their spores at a much earlier period than any 

 of the others that were growing in his cultures. As soon 

 as these spores made their appearance he raised the tem- 

 perature to 80 C., with the result that all those bacteria, 

 in which spores were not already developed, were very 

 rapidly destroyed ; the tetanus bacilli were also destroyed 

 (that is, the vegetative forms were destroyed), but the spores 

 still retained their vitality, and on being transferred to 

 suitable nutrient media, and placed under other suitable 

 conditions, they " hatched " out into the vegetative form, and 

 a pure cultivation of the tetanus bacillus was obtained. It 

 is a rather curious fact that here, as in the case of diphtheria, 

 the organism seems to be localized at the actual point of 

 inoculation, for although, as we have seen, the bacilli, how- 

 ever numerous in the pus and in the walls of the abscess, and 

 in the infiltrated tissues immediately around the abscess, 



