iia 
Sept. 22, 1870] 
The question is one of much interest, and it may therefore 
well be asked why such a totally different verdict should have 
keen given in two cases, the analogy of which is so remarkable. 
The reason is, however, not difficult to find. Mere theoretical 
consi:lerations have been all-powerful in influencing the verdict, 
and in inducing those who are informed upon the subject to 
read the evidence in different ways. Living things manifest 
such complex properties that the whole notion of Lite has been 
shrouded in mystery. Biologists at first could not lring them- 
selves to believe—some cannot do so now—that the phenomena 
which living things manifest are absolutely dependeuc upon the 
properties of the variously organised matter entering into their 
composition. They were obliged to have recourse to some 
metaphysical entity—some ‘‘anima,” ‘‘archzeus,” or ‘* vital 
principle” —under whose directirg influence the living form was 
supposed to be built up, and upon whose persisting influence 
many of the phenomena of Life were supposed to depend. The 
aid of no similar metaphysical ‘‘ principle” has, however, been 
deemed necessary in order to account for crystallin2 structures and 
properties. It was in the main conce led by most phys‘cists, and 
the doctrine remained unquestioned by biologists, that matter of 
certain kinds might, by virtue of its own inherent properties, aided 
by certain favouring circumstances—and quite inJependently 
of all pre-existing germs—fall into such modes of collocation as 
to give rise to crystals. But, owing to the influence of the theo- 
retical considerations already mentioned concerning the nature 
of Life, a similar possibility could not easily be granted in re- 
ference to the origin of Living things. Was it not held that 
the living thing owed its structure or organisation to the active 
influence of a special and peculiar principle? This ‘* vital prin- 
ciple” was neither ordinary matter nor ordinary force, neither 
was it in any way derivable from either of these ; how then 
could it be supposed that the coming together of matter of any 
kind could give rise to a living thing?* The aggregate of pro- 
perties, which we designate by the word ‘‘ Life,” were not sup- 
posed to be dependent upon, to be, in fact, properties of the ma- 
terial aggregate which constituted the Living thing. Life was 
presumed to be due to the manifestations of a something 
altogether peculiar—of a ‘‘vital principle,” which was insepar- 
able from living matter. Doctrines akin to these having been 
already proclaimed and disseminated by the influential teach- 
ings of Paracelsus, Van Helmont, and others, it cannot be a 
matter for surprise that the brilliant demonstrations of Redi 
should have had a great influence in their time. Observation 
after observation appeared now to confirm the existence of a seem- 
ingly universal mode of origin of Living things—a mode too which 
was more in harmony with the philosophical views of the day 
than that which had hitherto been deemed possible. Doubts, 
however, soon sprang up. New means of observation opened 
up new questions for solution. And what has been the result ? 
Many battles have been fought, many victories have been won, 
and now the biological doctrines of the day have assumed an 
entirely new form. ‘The ever-increasing strides of Science have 
wrought the most fundamental changes in our notions concern- 
ing Life. Under the influence of the well-established doctrine 
concerning Persistence of Force—and more especially since the 
clear recognition of the subordinate doctrine as to the Cor- 
relation existing between the Physical and Vital forces—phy- 
siologists have now begun to recognise, and most unhesitatingly 
to express the opinion, that the phenomena manifested by living 
things are to be ascribed simply to the properties of the matter as 
it exists in such living things. No one has expressed himself 
more decidedly on this subject than Prof. Huxley himself, and he 
may fairly be taken as an exponent of the modern doctrines on 
this question. He says:+—‘‘Carbon, hydrogen, oxygen, 
and nitrogen are all lifeless bodies. Of these, carbon and 
oxygen unite in certain proportions and under certain 
conditions to give rise to carbonic acid; hydrogen and 
oxygen produce water; nitrogen and hydrogen give rise to am- 
monia. These new compounds, like the elementary bodies of 
which they are composed, are lifeless. But when they are 
brought together under certain conditions they give rise to the 
still more complex body, protoplasm ; and this protoplasm ex- 
hibits the phenomena of life. Isee no break in this series of 
steps in molecular complication, and I am unable to understand 
why the language, which is applicable to any one term of the 
series, may not be used to any of the others. We think fit to 
call different kinds of matter carbon, oxygen, hydrogen, and 
* Buffon, it is true, as Professor Huxley has pointed out, did make an 
attempt to reconcile two incompatible theories, 
t Fortnightly Review, Feb. 1869. 
NATURE 
411 
nitrogen ; and to speak of the various powers and activities of 
these substances as the properties of the matter of which they 
are composed. ... Is the case in any way changed when 
carbonic acid water and ammonia disappear, and in their place, 
under the influence of pre-existing protoplasm, an equivalent 
weight of the matter of Life makes its appearance? . . . What 
justification is there then for the assumption of the existence in 
the Living matter of a something which has no representative or 
correlative in the not-living matter which gave rise to it?” 
For Professor Huxley, then, and for all who hold similar 
opinions on this subject, the constitution and properties of living 
things are so far comparable with the constitution and proper- 
ties of crysta's, that both, in each case, are alike supposed to be 
the products of the combination of ordinary matter of different 
kinds. And, as might have been expected, nearly all the biolo- 
gists and physicists who hold these opinions, are now inclined 
to admit their belief in the fossbi/ity of the origination of living 
matter free from the influence, and independently, of all pre- 
existing living matter. They are quite content to admit that 
Redi’s doctrine may be wrong. Prof. Huxley, indeed, in his recent 
address, desires us to understand that this is an opinion to which 
he still adheres; he says :—‘‘I think it would be the height of 
presumption for any man to say that the conditions under which 
matter assumes the properties we call ‘vital,’ may not some day 
be artificially brought together.” 
Having reached this stage, having got rid of the supposed 
necessity for the intervention of a special ‘‘ vital principle” 
before living matter can come into existence, * I think it will be 
seen by all how very important it has become to look into the 
truth of Redi’s doctrine, which has found its best modern ex- 
pression in the phrase omne vivum ex vivo, seeing that that 
doctrine was born and nourished under the influence of the old, 
and now well-nigh effete, metaphysical notions concerning Life. 
Certainly, now that this theoretical barrier has been removed, 
we ought to inquire more carefully than ever whether there is 
still a sufficient warrant for the differest verdicts which have 
been given in answer to the questions as to whether crystals 
on the one hand, or living things on the other, do or do not 
originate de xove in this particular stage of the Earth’s history. 
Now, at all events, theory inclines no more to the one side 
than it does to the other; it is quite possible to reconcile this 
with either view. 
Seeing, therefore, that we may now act without fear as im- 
partial judges, let us inquire into the nature of the evidence 
which alone can be relied upon for the solution of these two 
questions. 
If living things are to come into being de ovo, they could, 
or, at all events, are only supposed to originate from the re- 
arrangement of matter which previously existed in a state of 
solution, And although it is known to be possible for certain 
kinds of pre-existing solid matter to assume a crystalline form, 
we will, for the present, confine our attention to the origin of 
crystals in an apparently homogeneous fluid. Each of these 
material forms, therefore, would have to commence as a smallest 
conceivable speck, and each would grow, though differently, 
by the formation of matter of like kind, under influences gene- 
rally similar to those which were influential in bringing about 
the primordial collocation. These primordial collocations, 
however, are hidden from our view, and will, perhaps for ever, 
remain so, As a matter of observation, all that we actually 
know concerning the origin of crystals or of certain living things 
in solutions is this. In previously homogeneous solutions of 
crystallisable matter, or in certain apparently homogeneous col- 
loidal solutions, we may, under certain conditions, see the 
minutest crystalst or living things, respectively, make their 
appearance. In both cases these are, at first, mere motionless 
specks, whose minimum visible stage may be less than ygy3q;5 th 
of an inch in diameter. It must either be presumed, in the 
case of such embryo living things (as most people do presume in 
the case of crystals), that these, even then, and however minute, 
represent siages in the growth of later material collocations 
which had been initiated under the combined influence of 
existing matter and ‘‘ conditions” at a point far beyond the reach 
of our most aided vision ; or, on the other hand, it is equally 
* It may perhaps beas well to state here that I have not much expecta~ 
tion of influencing those whose belief in the existence of a special “‘ vital 
principle” remains still unshaken. 
+ The appearance of the crystals is best watched in the viscid solutions de- 
scribed by Mr. Rainey; since the rapidity of the process is thereby very 
much diminished, and the forms themselves are also more akin to those of 
living things. See his work On the Modes of Formations of the Shelt 
oY Animals, &c., 1858, p. 9- 
