Sovw Points in the Life-history of Bacterid. 129 



bacteriology. All three types — Bacillus, Spirillmn, and Micro- 

 covci(,'i — have their representatives among the infective bacteria. 

 It would be interesting to enumerate these so far as they are 

 known, or are fairly presumed to exist. 



Some of the Infective [Pathogenic) Bacteria. — Micrococci have 

 been found in Suppurative Diseases (Pyaemia, abscesses) ; 

 Scarlet Fever ; Small-pox ; Puerperal Fever ; Erysipelas ; 

 Gonorrhoea (a coccus is found dividing in two directions — 

 Merisniopedia — adhering to the pus-cells, and it is claimed 

 that pure cultivations were inoculable) ; Pneumonia^ (the so- 

 called Pneumo-coccus, certainly inoculable into mice, which died) : 

 Spirilla, in Relapsing Fever and Cholera asiatica : Bacilli, in 

 Leprosy ; Typhoid ; Plague ; Tuberculosis ; Anthrax ; Glanders ; 

 Tetanus. 



Generally, these visitants are not long sojourners, although 

 there are such notable exceptions as the bacilli of tubercle and of 

 leprosy. Either the patient or the microbe soon gets the upper 

 hand. In the former case a more or less lasting immunity 

 becomes established, as I shall explain presently. Adhering to 

 my original intention, I prefer to give you some leading points 

 about two most interesting cases of infectivity rather than to run 

 rapidly through the whole scale. The two cases which I select 

 are cholera and tuberculosis, of which latter consumption is a 

 particular and the most important case. These two diseases 

 stand at the extremes of duration, cholera carrying off its 

 victims in a few hours, while in consumption man plays a long- 

 drawn but too often losing game of months or years. Yet they 

 have this in common, that they are amongst the "grim reaper's" 

 most stalwart henchmen. They slay their hecatombs : cholera 

 over small areas quickly, with remissions or intermissions ; con- 

 sumption over nearly the whole inhabited world, slowly, but 

 without halting. They have this other fact in common, that we 

 owe it to the same distinguished scientist, Koch of Berlin, to 

 have discovered their respective microbes. 



CnoLEfeA. — The Spirillum cholerce-asiaticm is often called Koch's 

 comma bacillus, because individual cells, being only small 

 sections of a spiral, have that appearance when detached from 

 one another. Sometimes, however, they remain connected, and 

 the truly spiral structure becomes manifest. It is a great air- 

 lover in what may be called its natural state, and exerts its very 

 free powers of movement to get to it. This is one of the bacteria 

 of which we can say for certain that it lives two lives — one a 

 non-parasitic, or saprophytic {axir^ov, decayed or dead matter), 

 and also aerobic ; the other a parasitic and anaerobic. In water 

 which contains plenty of organic matter it can live and multiply. 

 Such a condition is supplied by the waters of the Ganges at its 

 mouths. Here is plenty of warmth and plenty of organic matter, 



