374 



BOTANY 



PART II 



is brought about by the excretion of poisonous substances, to which the name 

 toxins has been given. The following forms may be mentioned. Staphylococcus 

 pyogenes (Fig. 298 a), the cocci of which form irregular or racemose masses, is 



the most common cause of suppuration, 

 while Streptococcus pyogenes (Fig. 298 &), 

 with cocci united in chains, occurs in ery- 

 sipelas and other suppurative lesions. 

 Micrococcus (Diplococcus) gonorrhoeae (Figs. 

 298 c, 299 a) has somewhat flattened cocci 

 arranged in pairs, and causes gonorrhoea. 

 Bacillus anthracis (Figs. 298 d, 299 c) 

 was found by R. KOCH in the blood and 

 organs of animals suffering from splenic 

 fever. The relatively large rod -shaped 

 cells may be united in short chains ; they 

 form endospores in cultures in the same 

 way as the Hay bacillus. Bacillus tetani 

 (Fig. 298 e] occurs in the soil, and is the 

 cause of tetanus. Its straight rod-shaped 

 cells are ciliated, and grow only in the 

 wound itself; their spores are formed in 

 the swollen end. Bacillus influenzae, short, 

 slender rods ; Bacillus pestis, small, stout, 

 non-motile rods. LOFFLER'S Bacillus diph- 



theriae (Fig. 298 /) consists of small rod-shaped cells sometimes thickened at one 

 end. KOCH'S Mycobacterium tuberculosis (Figs. 298 g, 299 6), which is found in all 

 tuberculous lesions and secretions, and in the sputum, is a slender, slightly curved 

 rod ; branched forms also occur. It is non-motile and does not form spores. For 



FIG. 297. Streptococcus mesenterioides. A, Iso- 

 lated cells without gelatinous sheath ; 

 B, C, formation of chain of cells with 

 gelatinous sheath ; D, portion of mature 

 zoogloea ; E, formation of isolated cells in 

 the filaments of the zoogloea. (x 520. 

 After VAN TIEGHEM.) 



FIG. 298. Pathogenic Bacteria, a, Pus cocci ; &, erysipelas cocci ; c, gonorrhoea cocci ; d, splenic 

 fever bacilli ; e, tetanus bacilli ; /, diphtheria bacilli ; g, tubercle bacilli ; h, typhoid bacilli ; 

 i, colon bacilli ; k, cholera vibrios, (x about 1500. From A. FISCHER, Vorles. uber Bacterien.) 



these reasons it is grouped with some other species in a special family, the 

 Mycobacteriaceae ( 8 ). Typhoid fever is caused by the ciliated cells of Bacillus 

 typhi (Fig. 298 h) ; Bacillus coli (Fig. 298 i), the colon bacillus, which is as a 

 rule harmless and always occurs in the human intestine, closely resembles the 

 typhoid bacillus. The comma bacillus of Asiatic cholera, Vibrio cholerae (Fig. 298 &), 



