8 
investigation. If heterogeny obtains at all 
the result of the most careful experiments 
shows it to be confined to the most simple or- 
ganic structures ; and more highly developed 
forms are, as far as the most enlarged experi- 
ence shows, generated by reproduction. The 
great difficulty which is met with at the thres- 
hold of inquiry into the orgin of species, is the 
definition; in fact, species can hardly be de- 
fined without begging the question in dispute. 
Unless the advocate of continuity can, on his 
side, prove the whole question in dispute by 
showing that all species can directly or by inter- 
mediate varieties reproduce, he is defeated by 
the definition itself of species. On the other 
hand, if it be admitted that distinct species 
can, under certain favourable conditions, pro- 
duce intermediate offspring capable of repro- 
duction, then continuity in some mode or 
other is admitted. The doctrine of gradual 
succession is hardly yet formularized ; and 
though there are some high authorities for 
certain modifications of such view, the pre- 
ponderance of authority would necessarily be 
on the other side- Geology and Palaeontology 
are recent sciences, and we cannot tell what 
the older authors would have thought or 
written, had the more recently discovered facts 
been presented to their view. Authority, 
therefore, does not much help us on this ques- 
tion. Geological discoveries seemed, in the 
early period of the science, to show the com- 
plete extinction of certain species and the 
appearance of new ones, great gaps existing 
between the characteristics of the extinct and 
the new species. As science advanced, these 
were more or less filled up : the apparent 
difficulty of admitting unlimited modification 
of species would seem to have arisen from the 
comparison of the extreme ends of the scale, 
where the intermediate links or some of them 
were wanting. To suppose a Zoophyte the 
progenitor ef a Mammal, or to suppose at some 
particular period of time a highly developed 
animal to have come out of nothing, or sud- 
denly to have grown out of inorganic matter, 
would appear at first sight equally extravagant 
hypotheses. As an effort of Almighty creative 
power, neither of these alternatives presents 
more difficulty than the other ; hut as we have 
no means of ascertaining how creative power 
worked, hut by an examination and study of 
the works themselves, we are not likely to get 
either side proved by ocular demonstration. 
A single phase in the progress of trans- 
mutation would probably require a term 
far transcending all that embraced by historical 
records ; and, on the other hand, it might be 
said, sudden creations, though taking place 
frequently, if viewed with refereuce to the 
immensity of time involved in geological 
periods, may be so rare with reference to our 
experience, and so difficult of clear authentica- 
tion, that the non-observation of such instances 
cannot be regarded as absolute disproof of their 
possible occurrence. As undoubted cases of 
variation, more or less permanent, from given 
characteristics, are produced b y the effects of 
climate, food, domestication, &c., the more 
species are increased byintercalation, the more 
the distinctions slide down towards those which 
are within the limits of such observed devia- 
tions ; while, on the other hand, to suppose 
the more and more frequent occurrence of fresh 
creations out of amorphous matter is a multi- 
plication of miracles, or special interventions, 
not in accordance with what we see of the 
uniform and gradual progress of nature either 
in the organic or inorganic world. The more 
we observe, the more we increase the subdivi- 
sion of species, and consequently, the number 
of these supposed creations; so that new 
creations become innumerable, and yet of these 
we have no one well authenticated instance, and 
in no other observed operation of Nature have 
we seen this want of continuity — these frequent 
abrupt deviations from uniformity, each of 
which is a miracle. The difficulty of producing 
intermediate offspring from what are termed 
distinct species, and the infecundity in many 
instances of hybrids, are used as strong argu- 
ments against continuity of succession ; 
on the other hand, it may be said, 
long-continued variation through countless 
generations has given rise to such differences 
of physical character, that reproduction is 
difficult in some cases, and in others impos- 
sible. Suppose, for instance, a parent race 
whose offspring by successive changes through 
ages of time have divaricated and produced 
two widely different species, the changes here 
have been so great that we should never expect 
directly to produce an intermediate between the 
two species. On the other hand each of these 
species might reproduce with two other species 
resembling either of them respectively, and 
resembling each other more nearly than the 
first mentioned two. Yet, to regain the ori- 
ginal parent race or type, we must not only re- 
trocede through all the intermediates, but 
must have similar circumstances recalled in an 
inverse order at each phase of retrogression, 
conditions which it is obviously impossible to 
fulfil. But, though among the higher forms 
of organic structure we cannot retrace the 
effects cf time, and produce intermediate types, 
yet among some of the lower forms we find it 
difficult to assign any line of specific demarca- 
tion. Mr. Grove then adverts to some of the 
facts and authorities bearing on the derivate 
hypothesis, to the possible effects of climate 
and habits. If an animal seeks its food or 
safety by climbing trees, its claws will become 
more prehensile, the muscles which act upon 
those claws must become more developed, the 
body will become agile by the very exercise 
which is necessary to it, and each portion of 
the frame will mould itself to the wants of 
the animal by the effect on it of the habits of 
the animal. Another series of facts, says Mr. 
