40 



BACTERIA. 



but also deprive the blood of its oxygen. Vegetative cells only 

 occur in living animals. This species is a facultative parasite which 

 in the first stage is a saprophyte, and only in this condition forms 

 spores. 



Bacillus tuberculosis produces tuberculosis in human beings, also 

 in domestic animals (perlsudit}. It is a distinct parasite, but may 

 also live saprophytically. It is rod-formed, often slightly bent, 

 and is recognised principally by its action with stains (when 

 stained with an alkaline solution of methyl-blue or carbolic f uch- 



FIG. 32. Anthrax bacillus (Bactl- FIG. 33. Anthrax bacillus. The formation of 



lus anthracis) with red i,b) and white the spores ; magnified 450 times, 



(a) blood- corpuscles. 



sin, it retains the colour for a long time even in solutions of mineral 

 acids, in contrast with the majority of well-known Bacteria): it 

 probably forms spores which are able to resist heat, cfryness, etc. 



Bacillus leprce produces leprosy ; Bacillus mallei produces glanders ; Bacillus 

 tetani, tetanus (the tetanus bacillus is very common in soil ; anaerobic) ; Bacillus 

 diphtheria, diphtheria; Bacillus typhosus, typhoid fever, etc. 



Pathogenic Spiral Bacteria. Spirochocte obermeieri (Fig 

 24) produces intermittent fever (febris recurrens) ; it makes its 

 appearance in the blood during the attacks of fever, but it is not 

 to be found during intervals when there is no fever. Obligate 

 parasite. 



Spirillum cholerce asiaticce (Microspira comma) without doubt 

 produces Asiatic cholera ; an exceedingly motile spirillum, which 

 is also found in short, bent rods (known as the "Comma-bacillus"), 



