254 RELATION OF PLANT PROTOPLASM TO ENVIRONMENT 



Fischerella thermalis Gomont. 

 Dichothrix montana Tilden. 

 Dichothrix compacta Born. & Flah 

 Dichothrix gypsophila Bornet. 

 Calothrix thermalis Hansgirg. 

 Calothrix kuntzei Richter. 

 Calothrix calida Richter. 



Lyngbya nigra Agardh. 

 Lyngbya martensiana Menegh. 

 Aulosira thermalis West. 

 Symploca thermalis Gomont. 

 Inactis hawaiensis De Toni. 

 Plectonema nostocorum Bornet. 

 Hapalosiphon laminosus Hansgirg. 

 Hapalosiphon major Tilden. 



In regard to these and other thermophilic organisms mentioned by him, a 

 well-known biologist says: "no one doubts that in all the cases cited above, the 

 individuals living in hot springs have been derived from ancestors which lived in 

 water whose temperature rarely exceeded 40° C. The race has therefore become 

 acclimatized, and the question arises: How has that acclimatization been 

 effected?" The writer confesses to being one who would entirely reject the 

 first statement, and who considers that while acclimatization of organisms is 

 constantly proceeding, in the above group we have a primitive unacclimated 

 series, from which cooler species have descended by acclimatization modification. 



We would at once sum up our position by saying that we would regard these 

 41 species of thermophilic algae as (1) persisting remnants of what was once a 

 greatly more extended, continuous and abundant hot-water flora; (2) that they 

 now live in waters richly charged with all the chemical ingredients — phosphorus 

 at times excepted — needed for plant nutrition and growth ; (3) that they are now 

 forming extensive sinter or travertine deposits of siliceous or calcareous nature 

 exactly like rock beds that can be traced back through the geologic formations 

 to the mid-Archaean or Proterozoic rocks; (4) that the conditions under which 

 they now live are probably — almost certainly — identical with those to which they 

 have been exposed for untold ages; (5) that these conditions, though now 

 restricted to limited areas of the earth (like the Yellowstone, Mammoth Spring, 

 Sonoma and others in N. America, the Carlsbad in Bohemia, the Bormio, Lipari 

 and others in Italy, those of Iceland, the Azores, Himalayas, New Zealand and 

 Japan to mention only some of the best known) were once more prevalent, and 

 during the Archaean epoch probably covered a large area of the earth's surface; 

 (6) that in such warm waters, rich in chemical substances and in electro-chemical 

 activities, we might well look for the first beginnings of life ; (7) that these living 

 thermophilic algae are probably the surviving representatives of such anciently 

 originating types ; (8) that they, along with the thermophilic bacteria, suggest 

 stages in the gradual evolution or devolution of elaborating phycocyanin, carotin 

 and chlorophyllin pigments ; (9) that the now more abundant species inhabiting 

 cooler habitats, which are also exposed to less stimulating chemico-physical 

 environment, are forms which have become cooled down with gradual cooling 



of the earth's crust, and with restricted exhibition of volcanic activity. 



The above categories we will now shortly take up in succession, 

 suggests that a more extended and abundant thermal flora once existed. When 



The first 



