74 
The experiments on the spatial perception of two 
simultaneous sounds of similar quality are of special 
interest. Such sounds coalesce and give rise to a re- 
sultant or, as Prof. Pierce aptly calls it, phantom sound. 
As a rule this phantom sound is located at a position 
intermediate between those to which the observer would 
refer the two real components. These experiments with 
two coalescing sounds, not being liable to the same 
extent as those with one sound to the error introduced 
by unconscious movements of the head, may be of use 
to check such errors and to show that they exist. A very 
curious case, or set of cases, is examined by Prof. Pierce, 
who gives very fully the results of his own experiments 
and of those of other investigators. When the two 
component sounds, one on each side, are produced near 
the ears (4 cm. or less from each ear), the phantom is 
heard within the crantum and can be made to move 
inside the head towards the one or the other ear by vary- 
ing the relative loudness of the components. When the 
distance of the two sounds from each of the ears is 8 cm. 
or more, the phantom is extra-cranial. 
What seemed the most interesting points discussed in 
this essay have been noted ; but the whole of it is inter- 
esting, and physicists and physiologists will find it well 
worth careful reading. The fairly complete bibliography 
annexed to it greatly adds to its value. 
The second part of the book deals with some optical 
illusions, which are discussed with great critical acumen. 
: ALEX. CRUM BROWN. 
THE MORPHOLOGICAL VALUE OF THE 
CENTROSOME. 
Das Problem der Befruchtung. Von Dr. Th. Boveri. 
Pp. 48. (Jena: Gustav Fischer, 1902.) Price Mk. 1°80. 
ROF. BOVERI is so well known as a cytologist 
that anything from his pen will be read with 
interest. He is concerned in the little work before us in 
presenting in a non-technical fashion the main morpho- 
logical peculiarities connected with fertilisation, and he 
also discusses the meaning of the processes involved. 
The appendix will probably be regarded by many as the 
most interesting part of the whole, as he there critically 
examines the results which have been obtained by Loeb 
on artificial parthenogenesis, and which have been con- 
firmed and further investigated by Wilson. It will be 
within the recollection of some people that Loeb dis- 
covered the important fact that it is possible to induce 
normal development in w7/fertzlised eggs of certain marine 
animals by treating them for some time with a 12 per 
cent. solution of magnesium chloride in seawater, and 
then retransferring the eggs tonormal seawater. Morgan 
and others had previously found that the addition of 
salts of various kinds to the water sufficed to produce 
bodies remarkably like centrospheres, but it was not until 
Wilson showed this also to occur in Loeb’s experiments, 
and that they almost certainly initiate the process of 
segmentation, that the significance of the earlier results 
became apparent. 
Now the egg is normally destitute of any centrosome, 
and it has been thought on many grounds that one of 
the chief uses of the sperm was to import this body into 
the protoplasm of the inert ovum. Boveri himself first 
NO. 1699, VOL. 66] 
NATURE 
[May 22, 1902 
put forward this view, and he now seems inclined to 
admit that it may demand some degree of modification. 
His original conception of the sperm as starting the cyto- 
plasmic activities remains untouched, but obviously the 
nature of the mechanism involved is, as he says, open to 
a different interpretation from that originally assigned to 
it by himself, For it may now be fairly argued that it is 
not a centrosome as an organised structure which is intro- 
duced into the egg, and which there starts the segmenta- 
tion processes, but rather a chemical substance which, 
in combination with the ovian cytoplasm, produces 
the body in question. Such a view would reconcile 
much that has hitherto been difficult of explanation in 
connection with the diverse behaviour of centrosomes in 
different organisms, and even in different cells and tissues 
of the same individual. j 
In cycads, for example, centrosome-like structures 
(blepharoplasts) are associated with the karyokinesis of 
the generative cell of the pollen tube, but they are absent 
from the rest of the antecedent cell-generations. Hence 
their morphological permanence can hardly be seriously 
maintained in such a case as this. Again, in many of the 
higher plants the spindle fibres which appear in the early — 
prophases of karyokinesis (e.g. in pollen-mother cells of 
the lily) originate at many different spots in the cell, and 
this may probably be correlated with the extrusion of 
nucleolar substance which was described in this instance 
as long ago as 1893. Furthermore, such a conception of 
the possible nature of centrosomes enables one to har- 
monise the peculiar quadripolar spindles so characteristic 
of the lobed spore-mother cells of many liverworts. 
It is clear, of course, that the acceptance of such a 
possible origin of centrosomes does not necessarily in- 
volve a denial of their possible permanence in other 
cases. But it does add another striking example to those 
cases in which a morphological character may be traced 
to physiological causes, the character itself only per- 
sisting for so long as the physiological stimulus continues 
to operate. J: Bogie 
ROSE CULTURE. 
The Book of the Rose. By the Rev. A. Foster-Melliar. 
Second edition, with 33 illustrations. Pp. xiv + 352. 
(London : Macmillan and Co., Ltd., 1902.) Price 6s. 
HE design of the author is “ to show how roses may be 
grown in the best possible manner so as to produce 
the finest blooms” ; and from his enthusiastic love and his 
long, successful culture of the flower, he has written 
such an exhaustive treatise that the reader who has the 
ambition, the energy and the means to follow his instruc- 
tions cannot fail to achieve success. He gives clear and 
comprehensive details as to soil, situation, selection and 
treatment, where to erect a throne for the queen of 
flowers, and the homage which must be paid by those 
devoted subjects who would win her most gracious 
smiles. With a loyal service, which is never disheartened, 
the knight of the rose must be eager to maintain her 
supremacy against all comers. Without metaphor, he 
who would grow roses in their perfect beauty, and, like 
the author of this book, would be rewarded with medals 
and trophies, must obey the immutable law, must work for 
his wage, must train for the race if he would.so run'that he: 7 
OM 
LOOT 
