Lzn
241
Lin
vqgeneration of damaged parts of the embiyo Is be-
ooming more clearly recogxuxed every day. The trend
of the best scientific thought is clearly evident in cur-
rent bioloffical literature. Thus I^fessor Wilson of
Columbia University in 1906 closes his admirable ex-
position of the course of recent research over the whole
held with the conclusion that "the study of the cell
has on the whole seemed to widen rather than to nar-
row the enormous gap that separates even the lowest
form of life from the inorganic world " (The Cell, 4.34).
In these words, however, ne is only affirming a fact to
which the distinguished Oxford biologist Dr. Haldane
also testifies: *'To any physiologist who candidly re-
views the progress of the last mty years, it must bo
perfectly evident that, so far from having advanced
towards a physico-chemical explanation oflife, we are
in appearance very much farther from one than we
were fifty years ago. We are now more definitely
aware of the obstacles to any advance in this direction,
and there is not the slightest indication that they will
be removed, but rather that with further increase of
knowledge and more refined methods of physical and
ehemicalinvestigation they will only appear more and
more difficult to surmount." (Nineteenth Centurv,
1898, p. 403). In Germany Hans Driesch of Heidcl-
beix is at the present day, perhaps, the most candid
and courageous advocate of vitalism among German
biologists of the first rank. Since 1899 he has pro-
claimed his belief in the "autonomy" and "dynam-
ical teleology " of the organism as a whole. The vital
factor he boldly designates "entelechy", or "psy-
choid", and recommends us to return to Aristotle for
the most helpful conception of the principle of life.
His views on some points are unfortunately and (piite
unnecessarily, as it seems to us, encumbered by Kan-
tian metaphysics; and he appears not to have adtv
quately grasped the Aristotelian notion of entclechy
as a constitutive principle of the living being. Still,
he has furnished valuable contributions Imth to science
and the philosophy of life.
Side by side with this vitalistic movement there continues, of course, an energetic section of represen- tatives of the old mechanical school in men like H&ckel, Loeb, Le Dantec, and Verworn, who still at- tempt physico-chemical explanations; but no new ar- guments have been adduced to jastify their claims. Many others, more cautious, aclopt the attitude of agnosticism. This position, as Reinke justly olv serves, has at least the merit of dispensing from the labour of thinking. The present neo- vitalistic reac- tion, however, as the outcome of very extensive and thorough-going research, is, we venture to think, the harbinger of a widespread return to more accurate science and a sounder philosophy in respect to this great problem. With ref^ard to the auestion of the origin of life, the whole weight of scientiuc evidence and auUiority during the past half centur\' lias gone to demonstrate with increasing cogency Harvey's axiom Omne vivena ex -vivo, that life never arises in this world save from a previous living l)eing. It claims even to have established Virchow's generalization (1858) Omnia cdlula ex cdluUiy and even Flemming's further advance (1882), Omnia nudeua e nncleo.
The history of vitalism, which we have thus briefly outlined, shows how the advance of biological re- search and the trend of the best modern scientific thought is moving steadily back in the direction of that conception of life to be found in the scholastic phiioeophy, itself based on the teaching of Aristotle. We shall now attempt a fuller positive treatment of the dodnne adopted by the great body of Catholic phi- kMophers.
II. Doctrine. — A. Science, — Life is that perfec- tion in a living beinf^ in virtue of which it is capable of self-movement or mmianent action. Motion, thus understood includes, besides change of locality, all alterations in quality or quantity, and all transition IX.— 16
from potentiality to actuality. The term is applied
onl^ analogically to God, wno is exempt from even
accidental modification. Self-movement of a being
is that effected by a principle intrinsic to the nature of
the beinff, though it may be excited or stimulated
from without. Immanent action is action of which
the terminus remains within the agent itself, e. g.
thought, sensation, nutrition. It is contrasted with
transiejxt action, of which the effect passes to a being
distinct from the agent, e. g. pushing, pulling, warm-
ing, et<5. Immanent activity can be the property only
of a principle which is an intrinsic constituent of the
agent. In contrast with the power of self-movement
inertia is a fundamental attrioute of inanimate mat-
ter. This can only be moved from without. There
are three grades of life essentially distinct: vegetative,
sentient or animal, and intellectual or spiritual life;
for the capacity for immanent action is of three kinds.
Vegetative operations result in the assimilation of
inaterial elements into the substance of the living be-
ing. In animal conscious life the vital act is a modifi-
cation of the sentient organic faculty ; whilst in rational
life the intellect expresses the object by a purely spir-
itual modification of itself. IJfe as we know it in this
world is always bound up with organized matter, that
is, with a material structure consisting of orgaas, or
heterogeneous parts, specialized for different func-
tions and combined into a whole.
The ultimate units of which all organisms, whether plant or animal, arc composed, are minute particles of protoplasm, callepf sixteen and so on. The specific shape and different organs of the future animal only grad- ually manifest themselves. At first the cells present the appearance of a bunch of grapes or the grains of a mulberry, the monda stage; the growth proceeds rap- idly, a cavitv forms itself inside and the blasiosphere stage is reached. Next, in the case of invertebrates, one part of the sphere invaginates or collapses inwards and the embr\'o now takes the shape of a small sac, the gastrula stage. In vertebrates instead of invagi- nation there is une<|ual growth of parts and the dfe- velopment continuing, the outlines of the nervous system, digestive cavity, viscera, heart, sense-organs, etc. ajjpear, and the specific type becomes more and more distinct, until there can lie recognized the struc ture of the particular animal — the fish, bird, or mam- mal. The entire organism, skin, bone, nerve, muscle, etc. is thus built up of cells, all derived by similar processes ultimatelv from the original germ cell. All the characteristic features of life and the formative power which constructs the whole edifice is thus jxw- scssed by this germ-cell, and the whole problem of life meets us here.
The chief phenomena of life can l>e seen in their simplest form in a unicellular organism, such as the amoeba. This is visible under the microsco|)e as a minute speck of transparent jelly-like 5^ti^^Q\\'dSK^«
