RELATION OF PLANT PROTOPLASM TO ENVIRONMENT. 253 



chromatin stains, become more and more prominent, though irregularly and 

 often widely scattered through the cell. In the higher thread forms like Oscill- 

 aioria and Lyngbya these granules are united into loosely coiled granular threads 

 of chromatin, which we regard as a primitive and evolving nuclear structure. 

 The geographical distribution of the genera and species is noteworthy, for 



it is safe to say that in no other grou 



pt possibly the mosses and to a less 



extent the ferns, both with small light spores 



many species included 



that show an extended, often even a world-wide distribution. It is rare indeed, 

 also, amongst higher or nucleate plants, that the same genus may include species 

 some of which are freshwater, some brackish and some marine. But we need 

 merely name the genera Glceocapsa y M erismopcedia , Oscillatoria, Symploca, and 

 Anabama as a few amongst others that are illustrative. 



All of the above-mentioned details and others to be presently considered, 

 strongly suggest that we have here to deal with a primitive, possibly the most 

 primitive plant group now surviving. In further support of this, and at the same 

 time opening up, as we believe, a highly suggestive line of investigation, is that 

 morphologically diverse but physiologically similar series of the group, that may 

 appropriately be called the "thermophile Schizophy ceae. " This includes some 

 17 genera and 40-41 species which are found at the present day over the entire 

 world, and inhabiting warm or even hot waters of geysers, hot springs, or warm 



mineral fountains. 



When the suggestion was first made, now nearly a century ago, by a careful 

 European botanist, that living algae grew and flourished at a temperature of 

 55°-65° C, the record was viewed with suspicion or even contempt. Now we 

 know that the estimate was understated for certain thermal species, and that 

 a temperature of 70°-75° C. is by no means prejudicial for some. The sub- 

 joined list represents the genera and species that have been accurately deter- 

 mined, and which can so live and grow in water above the maximum for other 

 plants, viz., 40°-45° C, that they may well be designated "thermophile species 

 (2, 3, 4). 



M 



Chroococcus thermophilics Wood. 

 Chroococcus varius A. Braun. 

 Synechocystis aquatilis Sauvageau 

 Synechococcus asruginosus Naegeli 

 Synechococcus curtus Setchell. 

 Gkeocapsa montana Ktitzing. 

 Glceocapsa ? violacea Rabenh . 

 Gkeocapsa thermalis Lemmerm. 

 Pleurocapsa caldaria Setchell . 

 Oscillatoria acuminata Gomont. 

 Oscillatoria sancta Kiitzing. 

 Oscillatoria boryana Bory. 

 Oscillatoria cortiana Menegh . 



Oscillatoria geminata Menegh. 

 Oscillatoria okeni Agardh. 

 Oscillatoria grunowiana Gomont. 

 Oscillatoria terebriformis Agardh. 

 Oscillatoria chalybea Mertens. 

 Oscillatoria animalis Agardh. 

 Oscillatoria numidica Gomont. 

 Spirulina subtilissima Kiitzing. 

 Spirulina caldaria Tilden . 

 Phormidium treleasei Gomont. 

 Phormidium laminosum Gomont. 

 Phormidium angustissimum West. 

 Phormidium purpurascens Gomont 





