618 
NATURE 
| April 26, 1883 
whence with the obliquity of the ecliptic = 23° 411, Stone’s 
places for a.p. 138 become— 
Longitude. Latitude. 
Var. Schmidt (Piazzi, xiii. 126) ... 180° 52’ ... —2° 58’ 
68 Virginis... ... ... 178° 53) B94 
As we have seen, Ptolemy’s rgth star of Virgo is placed in longi- 
tude 178° 0’, latitude — 3° 0’; but, as is well known, the longi- 
tudes of the Almagest are about one degree too small, Hence 
Schjellerup’s identification of the variable with Ptolemy’s star is 
likely to be correct ; the object deserves frequent attention. 
D’ArRREsT’s COMET.—With reference to the remarks last 
week in this column on the first announcement of the observa- 
tion of D’Arre-t’s comet in the Dun Echt Circular, Prof. 
Krueger, Director of the Observatory at Kiel, writes us from 
that establish vent, as the ‘‘Centralstelle fiir astronomische 
Telegramme,” as follows :—‘‘I wish to state with reference to 
No. 703, p. 589, as I have done in 4. WV. No. 2507 [not yet 
received], that Dr. Hartwig had not telegraphed any daily 
~ motion of the supposed comet D’Arrest on the 4th Apri!. The 
hypothetical daily motion was added by myself in the cable-tele- 
gram to Cambridge, U.S., because I assumed that the American 
astronomers were not in possession of an ephemeris. Lord 
Crawford received, as usual, the same telegram as Cambridge, 
U.S., with the additional note (in order to avoid double-tele- 
grams) that the telegram had been sent to America. European 
astronomers received only Dr. Hartwig’s original communica- 
tion.” 
ON THE SENSE OF COLOUR AMONGST SOME 
OF THE LOWER ANIMALS? 
T the meeting of the Linnean Society on Thurday, April 19, 
Sir John Lubbock read a paper on this subject. Some years 
ago M. Paul Bert made a series of interesting experiments with 
the cowmon Daphnia, or water-flea, which is so abundant in our 
ditches and pools. He exposed them to light of different colours, 
and he thougat himself justified in concluding from his observa- 
tions that their limits of vision at both ends of the spectrum are 
the same as our own, being limited by the red at one end, and 
the violet at the other. 
In a previous communication Sir John Lubbock showed, on 
the contrary, that they are not insensible to the ultra-violet 
rays, and that at that end of the spectrum their eyes were affected 
by light which we are unable to perceive. These experiments 
have recently been repeated by M. Merezkowski, who, however, 
maintains that, though the Daphnias prefer the yellow rays, 
which are the brightest of the spectrum, they are, im fact, at- 
tracted, not by the colour, but by the brightness; that, while 
conscious of the intensity of the light, they have no power to 
distinguish colours. Given an animal which prefers the brightest 
rays, it may seem difficult to distinguish between a mere pre- 
ference for light itself rather than for any particular colour. 
To test this, however, Sir John Lubbock took porcelain troughs 
about an inch deep, eight inches long, and three broad. In 
these he put fifty Daphmas, and then, na darkened chamber, 
threw upon them an electric spectrum arranged so that on each 
side of a given line the light was equal, and he found that an 
immense majority of the Daphnias preterred the green to the 
red end of the spectrum. Ayain, to select one out of many 
experiments, he took four troughs, and covered one-half of the 
first with a yellow solution, half of the second with a green solu- 
tion, half of the third with an opaque plate, and he threw 
over half of the fourth a certain amount of extra light by means 
of a mirror. He then found that in the first trough a large 
majority of the Da,hnias preferred being under the yellow 
liquid rather than in the exposed half; that in the second a 
large majority preferred being under the green liquid rather than 
in the exposed half; that in the third a large majority preferred 
the exposed half to that which was shaded ; ana in the fourth 
that a large majority preferred the half on which the extra 
amount of light was thrown, 
It is evident, then, that in the first and second troughs the 
Daphnias did not go under the solution for the sake of the shade, 
because other Daphnias placed by their side under similar 
conditions preferred a somewhat brighter light. 
It seems clear, therefore, that they were able to distinguish the 
yellow and green light, and that they preferred it to white light. 
No such result was given with blue or red solutions, In such 
* By Sir John Lubbock, Bart., M.P. 
cases the Daphnias always preferred the uncovered half of the 
trough. 
It is, of course, impossible absolutely to prove that they per- 
ceive colours, but these experiments certainly show that rays of 
various wave-lenyths produce distinct impressions on their eyes ; 
that they prefer rays of light of such wave-lengths as produce 
upon our eyes the impression of green and yellow. It is, of 
course, possible that rays of different wave-lengths produce 
different impressions upon their eyes, but yet that such impressions 
differ in a manner of which we have no conception. This, how- 
ever, seems improbable, and on the whele, therefore, it certainly 
does appear that Daphnias can distinguish not only different 
degrees of brightnes:, but also differences of colour. 
UNIVERSITY AND EDUCATIONAL 
INTELLIGENCE 
CAMBRIDGE.—Prof, Dewar commenced a short course on 
Chemical Technology in its relation to Organic Chemistry on 
April 23. 
Mr. Sedgwick is lecturing on the Embryology of Mammals 
and Birds, and Mr. Caldwell on the Morphology of Gephyrea, 
Brachiopoda, Polyzoa, Choetognatha, and Larval Forms, prac- 
tical work accompanying both courses, 
Dr. Hans Gadow is lecturing on the Tegumentary and Mus- 
cular Systems of the Vertebrata. 
Prof. Darwin’s lectures on the Theory of the Potential will 
include an account of Gauss’s treatment of those problems 
generally associated with the name of Green. 
The Demonstrator of Mechanism is giving a course of Me- 
chanics applied to the strains in winding, pumping, and blast 
engines, and in other machines. A practical class is being 
formed for instruction in Surveying. 
SOCIETIES AND ACADEMIES 
LONDON 
Royal Society, April 12.—‘‘ Introductory Note on Com- 
munications to be presented on the Physiology of the Carbo- 
hycrates in the Animal System.” By F. W. Pavy, M.D., 
F.R.S. 
My last communication (Proc. Roy. Soc., vol. xxxii. p. 418) 
was entitled ‘* A New Line of Research bearing on the Physio- 
logy of Sugar in the Animal System.” 
During the time which has since elapsed, I have been actively 
continuing my investigations in the direction started, and the 
re-ults obtained give an entirely new aspect to the whole subject 
of the physiology of the carbohydrates in the animal system. 
Modern research has shown that, besides the well-known 
carbohydrate principles, such as sugar, &c., there are several 
dextrins distinguishable by their optical properties and their 
cupric oxide reducing power, 
From the colloidal principle starch, which has no cupric oxide 
reducing power, principles (dextrins) are producible by the action 
of ferments possessing gradually-increasing cupric oxide reducing 
power until maltose is reached, which constitutes the final pro- 
duct, and which possess a little more than half the cupric oxide 
reducing power of glucose. 
This is one foundation point connected with the researches I 
have been conducting upon the physiology of the carbohydrates 
in the animal system. 
The other foundation point is that the various members of the 
carbohydrate group are brought into glucose by the agency of 
sulphuric acid and heat. 
Proceeding upon these facts, and taking the cupric oxide 
redacing power before and after subjection to the converting 
action of sulphuric acid and heat, I have prosecuted investiga- 
tions upon the transformation of the carbohydrates within the 
animal system with the result of acquiring knowledge of an 
altogether unexpected nature. 
Hitherto what has been observed as regards the transforma- 
tion of carbohydrates by the action of ferments and chemical 
agents, has been a change attended with increased hydration— 
for example, the passage of starch into the successive forms of 
dextrin and maltose and cane-sugar into glucose. 
The issue of the researches, however, which I have been con- 
ducting recently, is to demonstrate the passage of carbohydrates 
exactly in the opposite direction by the action of certain ferments 
existing within the animal system. 
Alike in the alimentary canal, the circulatory system, and the 
