438 TRANSACTIONS OF THE CANADIAN INSTITUTE. [Vou VIII. 
that it may have been about or slightly above 80° C. We are so ac- 
customed to think of living forms being destroyed at a temperature 
above 75° C. that we are not prepared to believe that a higher tempera- 
ture would leave unaffected living forms of a simple chemical constitu- 
tion, but that is because we attribute to all living forms a complex chemi- 
cal constitution which is easily affected by high temperatures. It is not 
inconceivable that of the forms of life we know even the simplest are 
highly complex and thus we cannot bring ourselves to understand that 
living forms may exist or could have existed which possess or possessed 
only a tithe of the properties which we attribute to living forms. With 
the simpler constitution temperatures somewhat above 80° C. may have 
been harmless in their effect on such ultramicroscopic organisms as may 
have first arisen. 
Once arisen the forms would continue and reproduce themselves 
just as the ultramicroscopic particles in living matter increase in size 
and reproduce themselves by division in order that there may be addi- 
tions to the protoplasm such as growth demands. It may be that 
countless forms of ultramicroscopic organisms developed and vanished 
before one arose endowed with the constitution and properties which 
would enable it to survive through all the physical conditions attendant - 
upon its origin. Such a form once brought into being* would start on 
its long career, out of it would develop the protoplasmic mass just 
visible under the highest powers of the microscope and gradually but 
eventually from that again the living cell, the parent form of all 
structures such as we ordinarily recognize as animal and, vegetable 
organisms. 
It may be objected that this explanation of the origin of life on the 
globe is based on conditions postulated by the Nebular Theory and 
that such high temperatures did not obtain if the earth was formed in 
the manner demanded by the Planetesimal Theory, as advanced by 
Chamberlin. In answer to this objection it may be said that the 
Planetesimal Theory does not exclude the occurrence of gaseous, molten 
and high temperature stages in the earth’s history. Chamberlin 
admits that the infalls of the planetesimals to form the earth would 
result in high temperatures, in volatilization of many constituents of the 
present solid globe and that the present high temperature in the earth’s 
interior which is assumed to be about 20,000° C. may have been inherited 
from an earlier stage. Further, according to Chamberlin the hydro- 
spheres first appeared when the earth had half its present diameter, 
that is when it was no larger than Mars is now. 
