262 RELATION OF PLANT PROTOPLASM TO ENVIRONMENT. 



it continued to flourish even at 60°-70° C, and ceased growth only at 80° C. It 

 was of a light yellow hue, and so contrasted with a snow-white form B. ilidzensis 

 capsulatus, whose optimum was 59°-60° C, which still grew and multiplied at 

 60°-70° C, but could endure a higher temperature. 



Miyoshi (11) found 9 types of bacterial organism in the thermal waters of 

 Yumoto, at 51°-70° C. Of these 5 were red-colored, and 4 were colorless forms. 

 Again Falcioni (12) found three varieties of what he identified as Bacillus thermo- 

 philics in the hot springs of Bullicame di Viterbo. If his identification is correct, 

 this would be the same organism as Rabinowitsch and others have found in 

 earth, manure, etc. Its optimum temperature was 60° C. 



Georgevitsch (13) found in the sulphur springs of Vranje, a variety of the 

 same bacillus which endured a temperature of 70° C. At 49°-50° C. it ceased to 

 grow or multiply; its optimum was 56°-60° C. when spore-formation took place; 

 at 68°-70° C. a reduction of vitality occurred. So for this as for several other 

 thermophilic bacteria the minimum temperature is 48°-50° C, the optimum is 

 about 58° C, and the maximum 70°-75° C. These results again are all similar 

 to those of Benignetti for the hot waters of Acqui in Piedmont, and so it is 

 probable that when world-wide studies have been made of the micro-organisms of 

 sulphur waters a likely agreement of these will be noted, if the bacteria at all 

 correspond to the blue-green algse. 



The literature on the thermophilic bacteria that inhabit soils, manure heaps 

 and even the alimentary tract of animals is already extensive, but is admirably 

 summarized by Ambroz up till a year ago (Central, fur Bakt., 48 (1911), 257). 

 These live in an optimum temperature of 55°-65° C, at 35°-40° C. they show 

 minimum dormancy, at 70°-75° C. the maximum is reached. Their widespread 

 abundance over probably the whole world, as Globig's tests would indicate, is one 

 of the biological surprises of recent years, but is perfectly in keeping with the 

 line of argument pursued in this paper. 



Considerable diversity of opinion has been expressed as to their origin and 

 biological significance. Below, the writer suggests a possible origin that may 

 connect them equally with other bacteria that live in ordinary temperatures, and 

 with the blue-green algae. And in this connection the observation of Rabino- 

 witsch (15) that of the eight types studied by her, the color varied from white 

 through gray-yellow to brown, red and gray-green is really important. 



Between the thermophilic bacteria and those which live at ordinary temper- 

 atures, all gradations have been studied. Thus Micrococcus prodigiosus has 

 been proved to have a wide adaptability of temperature range, while Eisenberg s 

 (16) recent experiments with Bacillus anthracis prove that it is active alike 

 at normal temperature and up to 70° C. 



If we review now the Schizomycetes as a whole, it seems to the writer entirely 

 warrantable to conclude, that the most primitive group is that of the Thio- 

 bacteriaceae or sulphur and iron precipitating species, which are partly thermo- 

 philic, and which alike in cell morphology and in formation of mineral deposits 



