470 
[Marcu 18, 1897 
Lepidoptera, form the subject of a paper, by Mr. A. G. Mayer, 
in the March number of the Zvz¢omologzst. Experiments have 
shown that reds, yellows, browns and blacks are always due to 
pigments. In some cases, greens, blues, violets, purples and 
whites are also due to pigments, and not, as is usually the 
case, to structural conditions, such as strice upon the scales, 
&c. Concerning the chemical nature of the pigment substances 
within the scales, little has as yet been made known. The 
white pigments in the Pieridee appear to be due to uric acid, 
and the red and yellow pigments to two closely related deriv- 
atives of uric acid. The green pigment found in several species 
of butterflies and moths has also been shown to consist of a 
derivative of uric acid. The results of a careful investigation 
leads Mr. Mayer to believe that the colours of many of the 
Lepidopteral imagos are derived from the hemolymph or blood 
of the chrysalis. It is well known that the most universal 
colours of the more lowly organised moths are the drab-grey 
and yellow-drab tints, and these are the colous which Mr. 
Mayer found were assumed by the hemolymph after exposure | 
to the air. The brilliant yellows, reds, &c., are the result of 
more complex chemical processes; but the colours can be 
manufactured to some extent by treating the hemolymph with 
certain reagents. In connection with the phenomena of pig- 
mentation it is noted that uric acid is never present in the 
hemolymph of the imago of Saturnidee, nor could Mr. Mayer 
detect it in the drab-coloured pigment of the outer edges of the 
wings. 
ATTENTION may here profitably be directed to a paper which, 
though at first sight may appear of purely medical interest, has 
an important bearing upon the results described in the pre- 
ceding paragraph. We refer to a brochure by Mr. J. Barker 
Smith, reprinted from the A/edical Press and Czrcular, 1896-97 
(Bailliére, Tindall, and Cox). Mr. Smith’s experiments suggest 
that urates may be excreted by the hair, and that uric acid 
plays a 70/e in respiration and in the formation of the red cor- 
puscles from nuclear elements. The discovery of urates in 
the hair is significant, for it naturally brings into consideration 
wool, feathers, fur, &c., as to colouration and use, and also 
adornment and odour with reference to excretion and sex. 
Should Mr. Smith’s results be verified, they indicate that one 
chemical of necessity determines many common characteristics 
in a large section of our fauna. Another noteworthy point in 
the paper is the description of a new and rapid method of 
estimating urates. 
Baron H. EGGers contributes a paper on the Gulf of 
Maracaybo to the Deztsche Geographische Biitter, referring 
specially to the asphalt springs of El Menito. The whole 
region is of great geographical interest, but is little known on 
account of its extremely unhealthy climate. El Menito itself 
is a rounded knoll about 1 km. in diameter, and dotted about 
on its surface is a number of small cones, from which streams a 
mixture of mud, water and asphalt. The asphalt is in general 
colder than the surrounding air, and hardens in a few days, 
usually in a much cleaner and purer condition than the familiar 
asphalt of Trinidad. The greatest output of asphalt from this 
region took place in1S85, when it amounted to 161,000 kilogs. , 
but since then the quantity has steadily diminished, chiefly from 
political causes. 
MANY and various are the lakes in the United States, but 
there is only one which occupies the crater of an extinct volcano ; 
it is the Crater lake of Southern Oregon, lying in the very heart 
of the Cascade range, and belonging to the great volcanic field 
of the north-west. A very instructive illustrated account of the 
features of this lake is contributed to the Vatcéonal Geographic 
Magazine by Mr. J. S. Diller, of the U.S. Geological Survey. 
The lake contains no fish, but a small crustacean flourishes in 
NO. 1429, VOL. 55]| 
\ 
its waters, and salamanders occur in abundance locally along 
the shore. According to observations made’ by Mr. B, W. 
Eyermann last summer, the temperature of the water decreases 
from a depth of 555 feet to the bottom (1623 feet). The results 
suggest that the bottom may still be warm fron volcanic heat, 
but more observations are needed to fully establish such an 
abnormal condition. Mr. Diller shows that Crater lake not 
only presents very attractive scenic features, but also affords a 
most instructive and interesting field for the study of volcanic 
geology. 
Mr. ScourFIELD’s plea fora fresh-water biological station im 
England is supported by Prof. Dr. Anton Fritsch, who, in a 
short article in Materal Sctence (March), shows that valuable 
work is being done on the fauna and flora of fresh water im 
Bohemiaand Germany. Prof. Fritsch hopes that England will 
soon likewise do her duty to fresh-water biology, by establishing 
a station where investigations can be carried on. Such an ‘in 
stitution would give results of a practical, as well as scientific 
value. In connection with this subject, and in evidence of the 
valuable work accomplished at the Biological Station of the 
University of Illinois, situated at Havana, on the Illinois River 
attention may be directed to a bulletin just received. By this 
publication Mr. Richard W. Sharpe makes a noteworthy “ Con- 
tribution to a Knowledge of the North-American Fresh-water 
Ostracoda included in the families Cytheridze and Cyprinidie.” 
No better evidence could be adduced of the valuable services 
rendered to science by the establishment of a national physical 
laboratory, than the following list of investigations published 
within the last few months in //cedemann’s Annalen, all 
emanating from Charlottenburg :—Herr K. Koble describes 
Helmholtz’s absolute electrodynamometer as constructed during 
the lifetime of Helmholtz at the Reichsanstalt, and which he 
| has employed to determine the electromotive force of Clark's 
cell ; Herr Willy Wien contributes a mathematical investigation 
of the formula required to determine the constants of the instru- 
ment; Herrn W. Jager and R. Wachsmuth describe a series 
of experiments on the cadmium cell, including a comparison of 
its electromotive force with that of Clark’s cell, and a deter- . 
mination of the variations of this element with the temperature ; 
Dr. L. Holborn and Herr W. Wien describe some important 
researches on measurement of low temperatures, including a 
comparison of the air and hydrogen thermometers ; and Herrn 
M. Thiesen; K. Scheel and H. Diesselhorst give an account of 
a series of determinations of the coefficient of expansion of 
water. 
As the result of work carried on in the same laboratory, Prof. 
Friedrich Kohlrausch, of Berlin, contributes to the Aznader 
papers on the following subjects :—On platinum electrodes and 
determinations of resistance; on the plugs of rheostats; on 
very rapid fluctuations of terrestrial magnetism; and on a 
thermometer for low temperatures, and a determination of the 
coefficient of expansion of petroleum-ether. The latter name 
is applied to a certain mixture of hydrocarbons whose boiling 
point is 33°, and specific gravity 0°6515 at 17°. This substance 
remains fluid down to the temperature of liquid air, when it 
becomes highly viscous. 
IN the Zeztschrift des Vereines deutscher Ingenteure, Dr. L. 7 
Holborn gives an account of Le Chatelier’s thermo-electric 
element, and shows how it may be applied to the continuous 
measurement of the temperature of a furnace, thus possessing 
considerable advantages over the pyrometers in common use. 
Writing in the BerZiner Sélsungsberichte, the same physicist de- 
scribes a number of observations on the coefficient of magnetisa- 
tion of different kinds of iron and steel, showing that in a feeble 
field of force the {coefficient in question is a linear function of 
