936 



SCIENCE. 



[N. S. Vol. XVII. No. 441. 



of organisms partly or wholly emergent 

 from the waters are difficult to ascertain 

 with certainty, but in the majority of such 

 cases which have come under my own ob- 

 servation, the only living portions of such 

 masses were comparatively cool. The 

 temperatures which seem sufficiently cer- 

 tain to place implicit confidence in were 

 taken with the following precautions: (1) 

 temperatures only of submerged tufts 

 were taken; (2) the bulb of the thermom- 

 eter was placed within, or just at, the 

 sample which was removed and preserved 

 for microscopical study; and (3) in a very 

 considerable number of eases, particularly 

 of the highest temperatures noted, samples 

 and temperatures were taken at the same 

 spot on different days, or times of the 

 year. 



The results of all these observations, 

 taken with the precautions indicated above, 

 give certain general results for the 

 strictly thermal waters — i. e., for waters 

 over 43°-45° C. The temperature results 

 may be indicated under a number of dif- 

 ferent heads: 



1. No animals were found in strictly 

 thermal waters, although careful search 

 was always made for them. 



2. No living diatoms were found in 

 strictly thermal waters. At times, a few 

 empty valves were found, but these may 

 easily have been blown in, since the 

 localities were in the neighborhood of ex- 

 tensive areas of diatomaceous earth. 



3. All the organisms found in my own 

 collecting in strictly thermal waters be- 

 long to the groups of plants designated as 

 Schizophyta, being either Sehizophyceas 

 (Cyanophyceffi) or Schizomycetes (Bac- 

 teria). These two groups possess a simple 

 morphology and peculiar cell-structure. 



4. The ehlorophyllose Schizophycese (or 

 Cyanophycea;) commonly continue up to 



65°-68° C, and in some eases, but scantily, 

 up to 75°-77° C. 



5. The chlorophylless Schizomycetes (or 

 bacterial forms) endure the highest tein- 

 peratui'es observed for living organisms, 

 being abundant at 70°-71° C. and being 

 found in some considerable quantity at 

 82° C. and at 89° C. 



6. The temperature of 89° C. is the 

 highest at which I have been able to find 

 any organisms living. This temperature 

 was taken at several different times and on 

 two separate days. The organism belongs 

 to the filamentous Schizomycetes. Search 

 was made most carefully at the 'geysers' of 

 Sonoma County, California, for green or- 

 ganisms at 93° C, as recorded by Brewer, 

 but no life was observed at any tempera- 

 ture above 68° C. 



7. Living organisms were found at 

 higher temperatures in siliceous waters 

 than in calcareous waters. 



8. The limits of life in the siliceous 

 waters, as determined by my own observa- 

 tions, are between 75° C. and 77° C. for 

 ehlorophyllose, and 89° C. for chlorophyl- 

 less Schizophyta. 



9. The limits of life in the calcareous 

 waters, as determined by my own observa- 

 tions, are between 60° C. and 63° C. for 

 ehlorophyllose Schizophyta and between 

 70° C. and 71° C. for chlorophylless 

 Schizophyta. 



10. No organisms were found in springs 

 reputed to have a decided acid reaction. 

 This needs more study, but where a strong 

 acid (sulphuric) character is given for a 

 spring, the watei-s are free even from 

 Schizophyta. 



A careful study of the species of thermal 

 Schizophyta shows several details of in- 

 terest. They are either filamentous or 

 unicellular, but in each ease the filaments 

 or cells are enclosed within a jelly, usually 

 abundant. Within the strictly thermal 



