Apri, 18, 1912] 
NATURE 
167 
describe the apparatus and the methods he em- 
ploys with sufficient detail; his acquaintance with 
e psychology of esthetics is defective; the 
analogies which he presses between tones and 
colours are unsound. Yet, despite these manifest 
shortcomings, the book is to be welcomed as the 
sincere attempt of an enthusiast, who has spent 
much time and money on his hobby, to give the 
world some idea of its interest and of its value. 
No doubt, seeing is here verily believing; but 
“it is easily imaginable, as Sir Hubert von 
strument and improvise for half an hour whilst 
atching the ever-varying combinations of colour 
an unspeakable delight, but of real health-giving 
effect on the sense of colour.” Apart from his 
absurd division of spectral colours on the basis 
of our musical scale, “the main advantages of 
colour-music as an art” would, as the author 
rightly says, “remain unaffected, and the force 
of the chief arguments, which can be advanced in 
‘support of it as a separate and distinct art, would 
ot be weakened in the least.”’ It is, as we have 
aid, impossible to describe such esthetic enjoy- 
ent; one must experience it. GaS. MM: 
nnals of the Royal Botanic Garden, Calcutta. 
Vol. xii., Part i. :—‘‘Asiatic Palms—Lepi- 
“The Species of Deemonorops.” Vol. i., Letter- 
press. Pp. vii+237. Price Rs, 8 or 12s. 
Vol. ii., Plates. Pp. vii+1og plates. Price 
Rs. 39 or 2l. 18s. (Calcutta: Printed at the 
Bengal Secretariat Press, 1911.) 
HE appearance of the first portion of Dr. 
eccari’s monographic account of the Asiatic 
_Lepidocaryee, devoted to the genus Calamus, was 
recorded in Nature of August 12, 1909. It 
affords us pleasure to announce now the appear- 
‘ance of a second instalment of this great work, 
dealing with the genus Demonorops, which, like 
Calamus itself, consists of ‘“Rotangs,” and, 
‘among the genera of Palmez, is only less im- 
/portant than Calamus because it includes a 
“smaller number of recognisable forms. 
The methods and the style adopted in the treat- 
‘ment of the previous genus have been followed 
in the case of Demonorops. These have already 
been noticed in detail, and, therefore, do not 
require further discussion. The ample descrip- 
‘tions and excellent illustrations are equal in merit 
to those in the earlier contribution, and this 
further instalment of the author’s monograph 
places systematic students once more under a 
great obligation to him and to the Calcutta 
‘Botanic Garden, of the “Annals” of which it 
‘orms part. All who are interested in palms will 
ook forward with interest to the conclusion of the 
task on which Dr. Beccari is engaged, and to 
hich, as the two contributions already at our 
isposal testify, he has devoted himself with such 
atient enthusiasm and so great a fund of 
accurate knowledge. 
NO. 2216, voL. 89] 
on the screen produced by the playing is not only | 
docaryee.”’ By Dr. Odoardo Beccari. Part ii. :— | 
| species of plants and animals, of which the 
| acquired. 
“use and injury.” 
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 
taken of anonymous communications. | 
is 
The Principle of Reflection in Spectroscopes. 
THE application of a reflector to pass light back 
through a prism, or prisms, is usually ascribed to 
Littrow. Thus Kayser writes (‘Handbuch der Spec- 
troscopie,” Bd. I., p. 513), “Der Erste, der Riickkehr 
der Strahlen zur Steigerung der Dispersion verwandte, 
war Littrow” (O. v. Littrow, Wien Ber., 47, ii., 
pp. 26-32, 1863). But this was certainly not the first 
use of the method. I learned it myself from Max- 
well (Phil. Trans., vol. 150, p. 78, 1860), who says, 
“The principle of reflecting light, so as to pass twice 
through the same prism, was employed by me in an 
instrument for combining colours made in 1856, and a 
reflecting instrument for observing the spectrum has 
been constructed by M. Porro.”’ 
I have not been able to find the reference to Porro; 
but it would seem that both Maxwell and Porro ante- 
dated Littrow. As to the advantages of the method 
there can be no doubt. RAYLEIGH. 
Acquired Characters and Stimuli. 
In my letter in Nature of March 21, I pointed out 
the fact that Dr. Archdall Reid does harm by declar- 
ing that the term ‘‘ acquired characters" as ordinarily 
used by biologists is not intelligible (is, in fact, non- 
sensical), giving as his reason that all characters are 
That is a ‘quibble,’ because the term 
used by Lamarck (which has been translated as 
“acquired characters ’’) is ‘‘ changements acquis,”’ and 
it is abundantly clear that the change spoken of by 
Lamarck is a change from the normal characters of 
a wild species. Such normal characters may be, of 
course, described as ‘‘acquired’’ when considered in 
comparison with those of the germ from which an 
individual develops. But that is not the comparison 
made by Lamarck or by anyone else who uses his 
term or the English modification of it, and it is a 
perversion of fact to pretend that it is. It is the plain 
fact that the acquired changes indicated by Lamarck 
are changes as compared with the normal characters 
of the species. There was no allusion in my letter 
to the terms ‘‘innate characters ” or ‘‘ congenital char- 
acters.” They, of course (as Dr. Reid says), 
do not mean the same thing as ‘congenital 
variation.” Dr. Reid in condemning them is 
beating a mannikin dragged in by himself, diverting 
attention from the matter in hand. The “acquired 
changes’’ or “‘acquired characters” of Lamarck are 
properly contrasted with normal characters and not 
with Dr. Reid’s imaginary congenital characters. 
| Considerations as to whether the blacksmith’s arm 
or that of an ordinary man is ‘“‘normal’’ are not to 
the point, since Lamarck was concerned with wild 
“normal 
specific form” and the ‘normal specific environment ”’ 
are understood and known in some detail. 
Nor is Dr. Reid justified in attempting to limit the 
influences under which ‘acquired changes” or de- 
partures from normal specific form are developed to 
A variety of factors of the en- 
