192 



Profs. P. F. Frarikland and Marshall Ward. 



But there are micro-organisms in other classes of waters, not 

 usually employed for domestic purposes on a large scale, e.g., the sea, 

 salt marshes and springs, sulphur springs, and mineral waters of 

 various kinds. As a rule, the bacteria of such waters are different from 

 the above, and often appear to be more restricted in species. Thus : — 



In the sea are found Sarcina litoralis (Oerst.) ; Bacterium fusiforme 

 (Warm.) ; B. Pfliigeri (Ludw.) ; Beggiatoa mirdbilis (Cohn) ; Phrag- 

 midothrix multiseptata (Engler) ; Bacterium litoreum (Warm.) ; Beg- 

 giatoa pellucida (Cohn) ; Spirochete gigantea (Warm.) ; Spirillum 

 volutans* (Warm.) ; S. sanguineum* (Ehrenb.) ; S. violaceum* 

 (Warm.) ; Monas Mulleri* (Warm.), and some others. Here, again, 

 an enormous field exists for further research. 



Spirillum PLosenbergii (Warm.) and S. attenuatum (Warm.), and 

 some other imperfectly studied forms, affect brackish waters ; while 

 Crenothrix polyspora, Cladothrix dichotoma, and Leptothrix ochracea 

 (Kiitz.) are described as especially occurring in stagnant waters rich 

 in iron,f and certain other species are found in sulphur springs, and 

 even secrete sulphur in their cells : — e.g., Beggiatoa alba, Monas 

 Okenii, Glathrocystis roseo-persicina, Sarcina sulphur ata (Winogr.), 

 Monas vinosa, and a series of other forms. £ 



Others, again, are met with in warm springs, e.g., Sphmrotilus 

 thermalis (Kiitz.), and Sph. lacteus (Kiitz.), JJetoniella lutea (Kiitz.), 

 Beggiatoa arachnoidea (Ag.), B. alba (Yauch.), and others. 



Many of the foregoing species, and others referred to in Appen- 

 dix B, p. 244, may be regarded as water-bacteria, i.e., as forms more or 

 less habituated to life in natural waters ; but, as already stated, some 

 must be looked upon as occasional intruders, introduced temporarily 

 with foreign matters. 



Owing to the importance of some of these forms in causing 

 diseases in man and other animals, it is necessary to look with grave 

 suspicion on waters that give evidence of their presence, and we must 

 devote special attention to these, as most closely connected with the 

 subject which we have in hand. 



The literature concerning these pathogenic forms in water is almost 

 daily increasing : quite recently Tils§ has found Staphylococcus pyo- 

 genes aureus in town water. 



Passing over the strong presumptive evidence that Koch's Spirillum 

 cholerce asiaticaz is an aquatic form native to the waters in Bengal, it 



* All these stand much in need of further investigation. 



f See Winogradsky, " Ueber Eisenbacterien," ' Bot. Zeitg.,' 1888, p. 261. 

 Crenothrix polyspora is merged into C. Kilhniana by Zopf ; but see Winogradsky, 

 ' Beitr. z. Morph. u. Phys. d. Bakt.,' 1888. 



X See Winogradsky, "Ueber Schwefelbacterien," 'Bot. Zeitg.,' 1887, pp. 480, 

 et seq., and ' Beitr. z. Morph. u. Phys. d. Bakt.,' 1888. 



§ " Bactcriologische Unters. der Freiburger Leitungswasser," 'Zeitschr. f. Hyg, 

 1890, vol. 9, pp. 282—322. 



