a en  ——eEEEeEOEEEeEoeEeEeEeEEEeEeEeEeEeEeEEeEeEeE—E——EEEE ee 
NOVEMBER 6, 1913] 
Power who not only created the laws, but formed 
matter and space. 
The book consists of three chapters, covering 
seventy-five pages, followed by a series of sub- 
sidiary chapters, which are termed notes, which 
extend another seventy-one pages. © The three 
chapters deal with general information about the 
sun, moon, and stars, diurnal motions of the 
heavenly bodies and comets. The treatment is 
quite elementary, clear, and brief, and the informa- 
tion accurate. The notes, which are twenty-six 
in number, treat of a miscellaneous set of subjects 
relating to astronomy, and may be considered 
in some cases as brief essays. The headings of 
some of these notes are as follows :—Aurore, 
magnetic storms, sun-spots, and prominences; 
seven methods of obtaining accurate time; 
eclipses; proofs of the earth’s rotundity, &c. 
_ The book is neatly produced, contains numerous 
illustrations, and will no doubt serve a useful 
purpose in drawing youthful minds to the subject 
of astronomy. 
LETTERS TO THE EDITOR. 
[The Editor does not hold himself responsible for 
opinions expressed by his correspondents. Neither 
can he undertake to return, or to correspond with 
the writers of, rejected manuscripts intended for 
this or any other part of Nature. No notice is 
taken of anonymous communications.] 
Philosophy of Vitalism. 
I THINK that I voice the feelings of all London 
zoologists when I say how grateful we all are both 
to the Zoological Board of the University of London 
and to the governing body of King’s College for the 
opportunity which they have afforded us of hearing 
the new philosophy of vitalism so brilliantly ex- 
pounded by Prof. Hans Driesch. 
Perhaps you would spare me a little space if I try 
to set forth some reasons why Prof. Driesch’s con- 
ceptions do not appear to me to be of much service 
in assisting the progress of zoology. 
At the outset, one or two preliminary remarks may 
be made. The question whether for any consistent 
system of philosophy, or attempt to explain the 
universe, an idealistic attitude must be adopted, and 
the question whether at the present juncture idealistic 
conceptions ought to be imported into zoological 
science are two entirely different things. 
The task of zoologists is not to explain the universe; 
it is the much humbler one of endeavouring to com- 
pare together zoological phenomena and to ascertain 
the rules governing them. All “explanation” is 
merely comparison; we endeavour so far as we can 
to express the more complex phenomena in terms of 
the simpler, and so to find uniformity and order be- 
neath an apparent welter of unconnected details. 
Now Prof. Driesch offers us an “entelechy,” i.e. a 
non-material, non-mechanical ‘‘arranging”’’ power, a 
rudimentary “ psychoid”? which knows its purpose and 
uses the materials at its disposal in order to effect that 
purpose. Does the conception of entelechy help us 
to collate zoological facts or not? 
It was invented to account for the remarkable fact 
that when the first two blastomeres of the egg of a 
sea-urchin are separated from one another each will 
give rise to a perfect larva of diminished size. Driesch 
NO. 2297, VOL. 92] 
NATURE 
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291 
argued that since in normal circumstances one of 
these. blastomeres would have given rise to half a 
larva, therefore when it is separated from its fellow 
some innate power must be at hand to rearrange 
| the materials of the blastomere so as to give rise to 
a whole larva. But if the conception of an entelechy 
will cut the Gordian knot of this difficulty, there are 
a great many cases where the facts seem to be totally 
inconsistent with the existence of an entelechy. 
If the tail of a lizard be broken off.a little bud is 
formed at the injured surface, from which in due time 
a new tail is developed. But if this bud be slightly 
indented by a prick from a knife two tails and not 
one are developed from the bud. 
What is the entelechy doing in this case? Is its 
purpose altered, and has it decided to use the mate- 
rials to make two tails? Are we not justified in 
saying that if an enielechy was invented to explain 
why one blastomere of a sea-urchin’s egg forms a 
whole larva, it must be rejected because it utterly 
fails to explain why the injured bud on a lizard’s 
tail makes two tails? 
Again, if, when the egg of a frog has divided into 
two blastomeres it be tightly clipped between two 
glass slides in order to prevent its rotating, and if 
the whole preparation be inverted, then there will 
often result a ghastly two-headed tadpole. Why does 
the entelechy allow its purpose to be upset by so 
small a thing as the inversion of the egg? Is this 
not a much less violent change than cutting the egg 
in two? Instances of this kind might be multiplied 
indefinitely, and they show that at the best the con- 
ception of an entelechy is of quite limited application. 
There is another conception which is far more helpful 
in binding together phenomena, and that is the idea 
of “organ-forming substance.” In the egg of Cyn- 
thia, an Ascidean, the development of which has been 
worked out by Conklin, these organ-forming sub- 
stances can be seen in the living egg. This case was 
not alluded to by Prof. Driesch, as it is one which is 
almost impossible to reconcile with his theory. In 
the egg of Cynthia there is a yellow substance in the 
outer layer of the protoplasm. This collects round 
the entering spermatozoon when the egg is fertilised, 
and eventually forms a crescent in one quadrant of 
the egg. As development proceeds it is relegated to 
certain cells in the segmenting egg, and is eventually 
used up in forming the longitudinal muscles of the 
tail of the Ascidean tadpole. Now it is possible to 
kill the cells containing this substance on one or 
both sides of the segmenting egg. If the cells on one 
side be killed then there results a larva devoid of 
muscles on one side of its tail. 
Now if we assume that normal development depends 
on the juxtaposition of certain organ-forming sub- 
stances in certain spatial relations to one another, 
then when the two-cell stage of the egg of a frog 
is inverted these substances can partially or totally 
rearrange themselves, not under the influence of an 
entelechy, but under the influence of gravity. So also 
in the regenerating lizard’s tail, the spatial relations 
of the organ-forming materials with respect to one 
another are altered by the indentation produced by 
the knife, and so two tails and not one develop. 
Whence do these organ-forming substances come? 
The development of the egg of Cynthia teaches us 
that they arise from the nucleus of the ripe egg, and 
that they are definitely arranged (in some cases at 
least) under the influence of the spermatozoon. The 
ectoderm-forming substance of the egg of Cynthia is 
contained in the nuclear sap of the unripe egg and 
is emitted when the nuclear membrane breaks down. 
“But,’’ Driesch will reply, ‘‘I have shown that the 
nuclei of a segmenting egg can be displaced from 
