292 
their normal positions without altering the result.” { 
Granted. When once fertilisation has been effected 
and the arrangement of materials in the cytoplasm 
fixed, the nuclei which result from the division of 
the zygote nucleus enter on a period of inactivity so 
far as influence on the cytoplasm is concerned. But 
this inactivity does not last for ever, for though the 
Cynthia tadpole is incapable of regenerating anything, 
that same tadpole metamorphosed into an adult 
Ascidian will regenerate any part that is cut off— 
even its head. In the same way Roux showed that 
when one blastomere of a frog’s egg is killed the 
surviving blastomere will give rise to half a tadpole; 
but that half-tadpole, if it lives, will post-generate 
the missing half, and this belated regeneration is 
oa mea by a migration of nuclei into the injured 
alf. 
It may be objected that it is difficult to imagine 
what kind of chemical composition an ‘‘ organ-forming 
substance ”’ possesses. This is true; it may be difficult 
to compare it with chemical substances found in dead 
matter, but our knowledge of the possible complica- 
tions of organic substance in living matter is as yet 
small. This at least may be said, the active agent in 
development and regeneration can be displaced from 
its original position, and can be divided into two, and 
such attributes are much more easily connected in 
our minds with a substance than with a non-material 
entity, which, Prof. Driesch assures us, is not in space. 
E. W. MacBribe. 
Imperial College of Science, October 28. 
The Piltdown Skull and Brain Cast. 
In suggesting that a reconstruction of the Piltdown 
skull, made by the use of casts of the actual frag- 
ments, is not trustworthy (Nature, October 30, p. oe, 
Prof. Elliot Smith does Dr. Smith Woodward and 
Mr. F, O. Barlow less than justice. The casts now 
in circulation are most accurate representations of the 
originals, and reflect the greatest credit on the 
modeller, Mr. Barlow. Anatomists* have had no diffi- 
culty in gaining the freest access to the actual 
specimens; even those who, like myself, regard the 
original reconstruction of the skull and brain cast as 
fundamentally erroneous, have had every privilege 
granted to them on repeated visits to see the Piltdown 
fragments in Dr. Smith Woodward’s keeping. A 
reconstruction made from casts is then just as trust- 
worthy as one made from the original fragments. 
You have already (Nature, October 16, p. 197) 
permitted me, by the use of a diagram, to demon- 
strate the errors in the original reconstruction; I also 
availed myself of that opportunity to show diagram- 
matically the only reconstruction which gives an ap- 
proximate symmetry to the right and left sides of the 
head, and, at the same time, places the parts in their 
proper anatomical positions. It is clear, from his 
letter (NaTURE, October 30, p. 267) that Prof. Elliot 
Smith knows of another method, one which fulfils 
the same conditions, but gives a much smaller brain- 
capacity. All that is necessary to convince me that 
he is right and I am wrong is a drawing of that 
reconstruction : one comparable with the drawings in 
my previous letter. I have articulated the fragments 
in the manner suggested in his letter, and find that 
the degree of asymmetry in his suggested reconstruc- 
tion is as great as in the original. It is possible that 
I have misinterpreted some of the indications given 
in his letter. Any error of this kind would be cleared 
up by a drawing. ArtTuHurR Keiru. 
Royal College of Surgeons, 
~ Lincoln’s Inn Fields, W.C. 
NO. 2297, VOL. 92] 
NATURE 
[NovEMBER 6, 1913. 
Pianoforte Touch. 
Pressure of other work has prevented me from 
replying earlier to Prof. Pickering’s letter in NATURE 
for July 31. It is, of course, difficult to express any — 
definite opinion about an experiment without fuller — 
knowledge of the circumstances than can be acquired 
from a mere written description; at the same time 
it appears to me very easy to suggest explanations 
for the failure of the experiment. To strike the same 
note a hundred times in succession is certainly a very 
severe test to impose on a person’s powers of dis-— 
crimination. In this connection it would be interest- 
ing to perform, for the sake of comparison, one — 
hundred tests of a totally different character, say the 
well-known tests of blindfolding a person and making 
him taste tea and coffee, according to a prearranged 
succession. It would be giving the hearer a fairer 
chance if the experiment were performed by playing 
over a short sequence of notes, say a simple melody 
a number of times in succession. I have always per- 
formed the test in this manner, and it has generally 
been successful. 
Then, again, there is evidently a certain knack 
about producing these touch effects, and though one 
may try to strike a note sometimes in a pressing or 
caressing manner, and sometimes sharply, it is quite 
easy to fail to produce the desired effects, especially 
if the note is struck by the fingers. The best results 
I have been able to get in this way have usually been 
produced by holding the wrists high above the key- 
board for a brilliant tone and right below the key- 
board (so as almost to pull the keys down) for a soft 
tone. In producing the same effects with a pneu- 
matic player, variation of the load on the regulating 
bellows by means of my sliding weight or some 
equivalent method produces sufficient differences, but 
the action of the feet in pedalling has so much effect 
on the touch that even here it is easy to fail, especially 
in experimenting where the performer consciously 
attempts to produce a particular effect and thinks of 
what he is doing. In the course of playing a com- 
position the touch control is easier, as the necessary 
movements of the hands and feet are performed un- 
consciously, the performer only being conscious of 
the effect produced and not thinking of why or how 
he moves his levers and pedals to produce that effect. 
Another point which has been overlooked in this 
discussion is that different makes of piano respond in. 
very different degrees to small differences of touch. 
I recently tested a number of different pianos, and 
found that the make which I always use was by far 
the most sensitive, while one of the least sensitive 
was similar to the piano used by our local musical 
society, thus accounting for the comparative harshness 
of some of the professional performances compared 
with my pneumatic effects. 
It is, of course, necessary to distinguish carefully 
between variations in quality of individual notes and 
variations in the quality of chords. The possibility 
of producing the latter variations in the pneumatic 
player is proved beyond doubt, and, to my mind, it 
is very largely the failure of either the instrument or 
the performer to produce a pleasing balance between 
the various components of a chord that renders the 
playing so mechanical and uninteresting. The usual 
effect is to produce with soft playing a heavy bass 
drowning a dull treble, and with loud playing a shrill 
treble drowning a weak bass. This effect is prob- 
ably due to a large extent to the action of the regu- 
lating bellows, which in the ordinary players are 
controlled by springs. In playing a chord a number 
of different striking hammers of unequal mass have 
to be set in motion by means of the air pressure, 
