604 D. T. MACDOUGAL 
evolution, is quite insignificant, while even the simpler forms of 
animals and plants are to be considered as types widely divergent 
from primitive self-generating matter, being removed from it by the 
slow but sure advances of untold millions of years of development. 
It is, therefore, as if we had observed the events and objects of 
yesterday and were called upon to read the history of the past cen- 
tury. In the search for supporting ideas upon which to base specu- 
lation, two conceptions serve as encouragement for a renewed attack 
upon this fascinating problem. One is embraced by Chamberlin’s 
planetesimal theory of the growth of the earth and the attendant 
modification of surface conditions, which necessarily showed a com- 
plex widely different from the present, and the other is one, growing 
in favor with physiologists, to the effect that the essential activities of 
living matter rest upon catalysis, and enzymatic processes, with the 
characteristic reaction velocities directly affected by internal and 
external limiting factors. The protamic nucleus may be taken to 
represent the first form in which self-generating matter might be said 
to have the characters of protoplasm, but previously to its synthesis 
there must have occurred an increasingly complex series of carbon 
compounds, with hydrogen, oxygen, nitrogen, sulphur, and phos- 
phorus, while iron, calcium, magnesium, and potassium are also 
involved in its activities at the present time. That these main con-. 
stituents were present in the atmosphere at partial pressures of 
varying intensity, and that unstable carbides,. nitrates, phosphides, 
and sulphides brought by infalling planetesimals were passing into 
more stable unions with the formation of hydrocarbons, ammonia, 
hydrogen phosphide, etc., is suggested by Chamberlin, and the 
possible interactions and combinations might result in the synthesis 
of very complex substances, well up toward the simpler forms of 
living matter. The hypothesis formulated by him also assumes that 
the surface of the earth was unworn piled talus, but little of which 
had gone into solution. The development of the hydrosphere 
moistening this layer, and forming pools and small bodies of water 
all exposed to the light of the sun, together with the variations in 
temperature, partly due to the heat of impact of infalling bodies, the 
influence of magnetic fields induced by bodies circulating about the 
earth would determine the paths of ions and electrons traversing 
