| 
Fune 4, 1885 | 
NATURE 
Ill 
ously been attracted to the subject, endeavoured to make accurate 
maps of these cold and hot spots. It was found that their distribu- 
tion on corresponding parts differed in different individuals, that 
the distribution on symmetrical parts of the body was different, 
that the number of cold spots was greater than the number of 
hot spots, that the relative abundance of the two kinds varied 
in different parts of the skin, and that, roughly speaking, there 
are two grades of spots, viz. those which react almost always- 
and those which react only half the time and with a compara- 
tively faint sensation. The spots, as a rule, are less than a 
millimetre in diameter, and they are easily exhausted. The sen- 
sation roused by a single stimulus often lasts, however, for some 
minutes after the removal of the stimulus. As the thermally 
sensitive spots move about as the skin moves, it 1s clear that 
they are in the skin and not below. On being cut from the 
skin and examined, the spots showed no structures with which 
the sensations could be associated. The spots were found quite 
as sensitive on scars as on the sound skin, Using the radiant- 
heat method described by Pollitzer, the hot spots were found to 
respond from eight to forty times more quickly to a given stimu- 
lus than the not-hot ones. The explanation of any sensation of 
heat on the not-hot spots appears to be that there is conducting 
heat through the skin, so that the stimulus finally reaches a hot 
spot. : 
THE death is announced of Mr. Alexander Croall, Curator of 
the Smith Institute, Stirling, and a botanist of some reputation. 
WE have just received Band vy. of the Verhandlungen des 
Vereins fiir naturwissenchaftliche Unterhaltung zu Hamburg, 
1878-1882 ; the title-page bears the date 1883 ; it appears to 
haye been published in monthly numbers. Was Band v. actually 
published until 1885? ‘There is no internal evidence against its 
appearance in 1883, but we fail to find any reference to certain 
papers in it in the published records for that year. This ambiguity 
as to date is awkward. The contents are varied and valuable, 
and embrace natural history in its broadest sense, as will be 
seen from the titles of some of the papers, such as ‘‘ Die Um- 
gestaltung unserer Gegend durch Wasser und Wind und die 
Abnahme des Wassers in unserem Gebiete ;” ‘‘ Die Variabilitat 
der Schmetterlinge in ihren verschiedenen Entwickelungs-Stadien, 
und der biologische Werth von Form, Farbe, und Zeichnung ;” 
“Die Entwickelung unserer Kenntnisse der Lander im Siiden 
von Amerika ;” ‘‘ Hammer und Messer in der Sprachgeschichte ;”” 
*Haben auch in Deutschland gleichzeitig mit dem Mammuth 
Menschen gelebt?” ‘* Die Insel Rotumah und ihre Bewohner ;” 
‘* Mittheilungen tiber einen Taifun bei Jokohama und Jeddo,” 
&c. Of the papers enumerated that on typhoons seems especially 
interesting on account of the analyses given of the reports of 
various ship-captains, There are several zoological and botanical 
papers, in addition to the one already quoted. 
THE new annual report of the Canadian Minister of Agri- 
culture to the Governor-General contains, for the first time, the 
report of the Dominion entomologist, Mr. James Fletcher. The 
Minister explains that as an acquaintance with the results of 
entomological science is a matter of necessity to every tiller of 
the soil, he took the step of appointing an official entomologist 
in order that the attention of those whose interests are materially 
affected might be called to the subject. As Mr. Fletcher was 
only appointed in June last year, his report is necessarily a pre- 
liminary one. He has succeeded in establishing a system of 
correspondence all over the Dominion, and from extracts of 
letters which are published in his report it is clear that he has 
ample work before him. In parts of Nova Scotia, for example, 
the cultivation of wheat has had to be abandoned, on account of 
the wheat-midge, or Diéglosis tritici. In other places, clover, 
peas, roots, fruit and forest trees have suffered heavily by the 
ravages of various insects. The position of entomologists, there- 
fore, is one with large possibilities of material benefit to the 
Dominion and its inhabitants. 
A SERIES of photographs of lightning flashes were lately ob- 
tained at Berlin by Dr. Kayser, and are the subject of a paper 
to the Academy there (Wed. Ann., No. 5). The lightning is 
shown (as previously) to have gone very often from one point to 
several, the aspect in the photograph being like that of a river 
with numerous tributaries (only the fluid takes the opposite 
direction). The weaker flashes did not so branch out. In one 
remarkable effect the stem consists not of one bright line only, 
but of four parallel throughout, the second being rather a band, 
and stratified transversely. The explanation Dr. Kayser offers 
is, that in this case there was an oscillating discharge, The first 
spark, in passing from cloud to earth, would leave a channel of 
heated air, which would be used by the next spark from earth to 
cloud, only it was meanwhile a little displaced by the wind ; and 
so with the others. Such oscillatory discharges may sometimes 
be observed with the eye in violent thunderstorms if the oscilla- 
tion be pretty slow. Dr. Kayser reckons the whole phenomenon 
in the present case to have occurred in less than half a second. 
The stratified appearance of the band he is unable to account 
for. 
THE eels of the ponds in the woods of Vincennes leave them 
every spring in large numbers, making their way to the Seine or 
the Marne, several kilometres distant. They take advantage of 
rainy weather, when the herbage is wet, and their instinct guides 
them directly to their destination. New species have repeatedly 
been introduced into the lakes, but in vain; all seem to have 
this disposition to leave. Some have thought that the water of 
these ponds, having been brought by hydraulic engines, has 
undergone some change which drives the eels away. But the 
phenomenon of such migrations by eels and some other fishes is 
not uncommon. Thus in the marshes of Picardy eels are often 
found on the grass, going from one pond to another. 
THE reports of the Aéronautical Society of Great Britain for 
the years 1883 and 1884 have just been issued together in a 
small volume. It is mainly occupied by papers read before the 
Society. Amongst these is one on the mechanics of flight and 
their application to flying machines, by Mr. H. Middleton ; 
artificial flight attainable by Mr. Hollands ; the possibility of 
man-flight, by Mr. Barry ; on the methods of soaring birds, and 
the bearing of the facts connected with them, by Mr. J. Lancaster, 
of Chicago. Amongst the shorter papers are: a visit to the 
Aéronautical Exhibition at Paris, by Mr. Frost ; a memoir of 
Mr. John Stringfellow, by Mr. Brearey ; a light and economical 
motor for propulsion in air, by Capt. Griffiths ; and conjoint 
gas and mechanical action as applied to flight, by Mr. Brearey. 
AN aéronautical exhibition under the patronage of the Aéro- 
nautical Society of Great Britain is to be opened during the 
present month in connection with the International Exhibition 
at the Alexandra Palace. The objects for exhibition will be 
models of designs for the accomplishment of aérial navigation by 
mechanical means only, or partly by buoyancy and partly by 
mechanical means; objects which are capable of flight and 
carrying their own motive power ; machines constructed upon a 
scale calculated to carry a weight equal to that of a man upon 
the principles advocated by the inventors ; light motors ; balloons, 
nayigable or otherwise ; balloon material’; kites, or similar aérial 
appliances, for saving life at sea, or for traction ; and other 
objects of interest connected with aéronauties. The large out- 
door space will be made available for various competitions, such 
as the nearest approach to a given locality. The disputed 
question of aérial locomotion by the aid of buoyancy will also be 
conclusively tested. 
THE scientific society, Isis, of Dresden, having recently 
attained the fiftieth year of its existence, has issued a special 
