aceous. 



still 



258 RELATION OF PLANT PROTOPLASM TO ENVIRONMENT. 



aspect of ordinary gray compact Paleozoic limestone. Sometimes they contain 

 a considerable amount of graphite, and some of the shales are highly carbon- 



In other places they are banded with layers and seams or nodules of 

 cherTin a manner closely similar to that in which the Carboniferous Limestone 

 of western Europe contains its siliceous material. Sometimes the chert bands 

 are as much as forty-five feet thick. The general character of these mingled 

 carbonaceous, calcareous and siliceous masses at once reminds the observer of 

 rocks which have undoubtedly been formed by the agency of organic life." 



The beds also of opals, opal marbles and other siliceous compounds, also the 

 marls and related carbonate rocks may in part at least have originated from the 

 akffi of hot-spring activity. But even as temporary masses of colloid silicates 

 and carbonates these sinters may often and widely have been deposited, to be 

 again redissolved, or withered for formation of other sedimentary rocks. The 

 evidence therefore seems fairly abundant and suggestive, that between the close 

 of the igneous period, and before the deposition of Cambrian rocks, deposits 

 were forming that can best be explained as due to the activity of plant organisms, 

 and not least of Schizophyceous algse. 



Sixth In approaching this topic it may be said that, during the past half 

 century , biologists have tried to account for, or to trace the beginnings of life in 



oceanic— even abyssmal— deposits or formations; in lagoons bordering the 

 „ where varied inorganic compounds can accumulate to interact on each other; 

 or again they have somewhat vaguely suggested the possibility of hot spring 

 areas as active centers of molecular change. The last seems to the writer the 

 only one that has much to be said in its favor. 



We now recognize fully that organic bodies are fundamentally colloid 

 aggregations. In hot springs colloid action and reaction are proceeding more 

 actively and steadily than in any other region of the world. All organic bodies 

 contain at least seven elements, which are either linked together in complex 

 manner as colloid molecules, or they aid by contact action in building up and 

 maintaining such molecules. As already noted, all of these elements except 

 phosphorus exist side by side in loose states of combination and under mgn 

 electro-chemical tension, in probably all of the hot springs of the world, tnougn 

 in siliceous springs like the Great Geyser, the silica predominates, m c ™ w ™™ 

 ones like the Mammoth geyser, lime predominates, while in the sulphur-bacter a 

 springs to be treated of below, the element sulphur predominates. 



The blue-green alga3 and the thermophilic bacteria are formed fundamentally 

 of a colloid pellicle that we may term mucilage-cellulose, and of enclosed pro - 

 plasm also of colloid nature, but of highly complex molecular composition, 

 latter excretes the former as a limiting osmosizing tension layer, much as 

 the enclosed substance in a Traube cell deposit the pellicle of diverse compos ^ 

 around it. More perfectly and on a larger scale in the post-igneous perl ° ly 

 the world's history than at any later time, areas must have existed that c 

 simulated the hot springs of to-day, and where molecular colloid interac 



