40 
even of the highest species, pass from the ovwm to the adult, 
exhibit the same gradation. The proposed argument is, that 
these analogies give an inductive proof that species are evolved 
from species by an equally natural law of evolution. 
Let it be again observed that all we need attempt, in 
criticising this supposed argument by the principles of induc- 
tion, is to show that the process is invalid. And we would 
preface the farther criticism by the caveat, that we do not 
admit the parallelism of the three sets of instances, in the 
sense claimed by evolutionists. The paleontologic series, for 
instance, in order to support this pretended evolutionist 
induction, should be a series of higher and more complete 
animal forms succeeding the more rudimental in time. But 
such it is not. At each paleontologic period, some of the 
four groups of living creatures are found coexisting, in at 
least some types of each, and not merely successive. The 
paleeozoic strata are found to contain vertebrate fishes, along 
with the radiates and molluscs of that first period. And, if 
we may trust Agassiz’s assertion, there is no evidence that 
the embryonic changes of any individual animal of a higher 
group exemplifies all the gradations from the lowest group 
up to its own. These mutations of its foetal life only illustrate 
fully the gradations of the species in its own group. 
But, waiving for the time these questions of fact, we show, 
in this pretended induction, this vital defect: it mistakes an 
analogy (an imperfect one) in the method of action of certain 
vital energies for a causal identity. The essential lnk of a 
demonstrative induction is lacking. If we take, for instance, 
the embryonic order of development, all that is proved by 
the multitude of cases colligated is, that the individual ova 
are all endued with a vital energy which causes, and thus 
insures, the growth of each individual into the matured type 
of its own species. Jor such, and such alone, is the result, as 
observed. In no single case has an individual ovum, be its 
analogy of mode of development to that of other species what it 
may, resulted in an evolution into a different species from its 
own. Hence, there is not a particle of inductive evidence that 
this causal energy which we see at work is competent to such 
evolution. Hach individual gives an instance of a development 
through an embryonic series? ‘True. But in every instance 
the development terminates within the strict limits of its 
own species; and the induction from the latter set of facts 
is precisely as broad and as inexorable as from the former. 
Again, the analogies noted all receive their sufficient solu- 
tion from another hypothesis, namely this, that they are the 
expressions of a common plan of thought, by which the 
