574 Reviews—Ridsdale’s Cosmic Evolution. 
acting in the evolution of Living Forms were first able to come 
into play. 
The Organic Aspect of Evolution.—The Harth being now fitted for 
it, a new and original force came into play; one different in its 
tendencies and unlike in its action to any of the previously-existing 
forces of Nature. ‘This force was Lirr. Ever since its first manifes- 
tation, while Inorganic Evolution has proceeded contemporaneously 
with it though in a milder and more subdued form, its power and 
scope of working has steadily increased.” 
Paleontology, as at present understood, certainly affords no record 
of that interesting period in the Earth’s history, when the Organic 
was evolved out of the Inorganic. It is quite in accordance with 
the author’s general views that such an evolution did take place, 
although he scarcely ventures to say so. He considers, likewise; 
that this growth of the Organic out of the Inorganic could only take 
place at one stage in the development of the Harth, and that, if such 
a thing were possible now, a serious blow would be struck at the 
doctrine of Evolution generally. 
It is most probable that the origin of Life will remain amongst 
the things unknowable: all that Paleontology can do is to trace 
the evidence backwards as far as practicable. In this connection 
some might be disposed to disagree with the author as to the 
evidence afforded of the alleged approximation of the two branches 
of life—animal and vegetable. Excluding such doubtful forms as 
Eozoon, which few now regard as having any connection with organic 
structure, the earliest certain forms of Life in the Lower Cambrian 
exhibit a considerable amount of differentiation, rendering it probable 
that Life had become a factor in the Earth’s history for a considerable 
period antecedent to this epoch. Hence it is by no means improbable 
that far more primitive forms existed which may have shown some- 
thing of the approximation to which the author refers. But where 
are their remains now? Shall we seek them in the Monian, the 
Pebidian, or any other of the rival systems, which appear to occupy 
the ground between the Cambrian and the Archean ? 
Although quite disposed to agree with the author in his general 
contention, there are some other statements of his in connection 
with Paleontology which seem open to criticism. He says (p. 48) 
that in early times, when the geological forces were more active, 
that stock had a tendency to survive whose members varied most. 
In a certain sense this may be so, but the history of the tetra- 
branchiate Cephalopoda presents us with an instance in the opposite 
direction. The steady-going Nautilus, though born long before his 
cousin the ever-changing Ammonite, alone survives. In fact, the 
author himself (p. 51) observes that a family succumbing either to 
slow alteration of the environment, or to inter-racial competition, 
always varies violently during the process. Indeed, the most sluggish 
genera, such as Lingula, but little affected, perhaps, by the environ- 
ment, and still less given to inter-racial competition, have been 
much the same throughout all epochs. In such a case the “ survival 
of the most inert” is applicable to certain forms of life. But this 
