186 
POPULAE SCIETnTOE l^EWS. 
[December, 1891. 
on the flower, uot in it like the two other forms. 
The last variety, pure piuk, is iuhabiteJ by a 
Thomisns which is also pink on the dorsal side of 
the abdomen and limbs. In fact, each of the 
three color varieties of Convolvulus is inhabited 
by a correspondingly colored variety of Thomisus. 
It has been generally considered that each of the 
spider varieties is a genuine variety. But this 
assumption is erroneous, as M. Heckel found out. 
He had put in a small box a number of pink 
Thomisus in order to send them to a friend for 
investigation ; but he forgot all about the box 
and its contents during a fortnight, and when he 
opened it again was astonished at seeing that all 
the Thomisus had lost their pink color. He took 
some of the animals and put them on differently 
colored flowers, and was much surprised after 
four days when he found each spider had taken 
the color of the flower it lived in. As specimens 
of the same Thomisus are often met in the yellow 
Antirrhinum and the red dahlia, he also put some 
of these uncolored specimens in these flowers, and 
he saw that they assumed a yellow or red color. 
The conclusion is, then, that there are no real and 
permanent color varieties of Thomisus onustus, but 
that the same animal may vary in color according 
to the color of the flower it has selected as lodg- 
ings. This fact is very interesting, and we feel 
inclined to accept it ; but M. Heckel has not given 
proofs enough yet, as he has not taken care to 
prevent the possibility of the uncolored spiders 
running away and leaving the place to be taken 
by others. A very simple experiment will settle 
the matter easily, and perhaps some of our read- 
ers might be induced to investigate the subject 
with other species of animals. 
Speaking of spiders, I would call the attention 
of the farmer to a paper which M. F. Terby has 
recently published in the Bevue Scientiflque. M. 
Terby is a Belgian entomologist, and has made 
some VHluable experiments and investigations 
concerning ballooning or flying spiders. Every 
one has met spiders sailing through the air and 
carried on long silk threads — the well-known gos- 
samer threads. I met some hardly an hour ago, 
in the bright, warm October day which is closing; 
and it is in October, when the young spiders are 
hatched, that the flying spiders arc most com- 
monly met. It would seem that the latter had 
already attracted the notice of old Aristotle; at 
all events, it is quite sure that over two centuries 
ago Stafford, Martin Lister, and John Ray de- 
scribed with much accuracy (Philosophical Trans- 
actions, 1658, 1669, 1670) the maimer in which the 
spiders climb on posts or stalks of giass, crouch 
down with their abdomen projecting as high as 
possible in the air, and, if some breeze, however 
slight, is present, send forth jets of silken fila- 
ments which float in the air and are sufficient to 
carry them off when they let go the blade of grass 
or other projecting support. An excellent ac- 
count of this operation is to be found in ^M. II. 
McCook's admirable American Spiders and Their 
Spinning Work, based on the observations of the 
numerous investigators who have devoted their 
time to the matter, and on those of the eminent 
writer himself. But one point has escaped M. 
McCook's attention, in observation as well as in 
reading : he has not been acquainted with a paper 
written by M. Terby in 1867 and published that 
year in the Bulletins de V Academic Boyale de Bel- 
gtque, and has not noticed the important fact 
therein described— that the spider sends forth its 
jets only under the influence of the motion of the 
air, and that one may at will induce it to do so 
merely by blowing on it softly, with the mouth, 
for instance. • As soon as there is some motion of 
the air the spider, when bent on "moving," of 
course, seems to be irresistibly impelled to send 
forth the gossamer. M. Terby"s papers will be 
found useful, as they contain, moreover, some 
notes on papers which M. McCook is not ac- 
quainted with. 
In a year or two Paris is to have one of the 
finest physiological laboratories, uot only of 
France, — which is saying but little, — but of Eu- 
rope. It is not that this laboi-atory shall be the 
largest or richest, but, being designed by a man 
who is an eminent physiologist, and who has a 
large experience, it will be one of the most con- 
veniently arranged. This laboratory is the one 
which is being at present built in the Paris Jardin 
des Plantes for and by Professor Chauveau. 
Everything has been devised by him, and, as he 
has his whole life worked at physiology, it is to 
be expected that he understands the way a physi- 
ological laboratory should be built. Here will be 
a striking contrast with the laboratories recently 
erected in the Medical School, which are really 
monuments — and, unfortunately, lasting monu- 
ments — of the imperishable silliness of French 
government architects. It would seem that when 
an architect knows so little of his business that 
no private individual would ever ask for his ser- 
vices, then the fatherly government steps in and 
says that he will do for government — that is, for 
puldic — building. And then that man is allowed 
to erect enormous buildings, at still more enor- 
mous cost, and they are conceived in such a man- 
ner that they are worthless. Positively the Eeole 
Pratique of the Medical School contains laborato- 
ries which are perfect wonders — in their way. 
Please never try to have the same in the United 
States. It is a friend's advice. ' II. 
Paris, Oct. 18, 1891. 
[Specially Observed for Popclae Science News.] 
METEOROLOGY FOR OCTOBER, 1891. 
TEMPERATURE. 
Average Thermometer. 
Lowest. 
Highest. 
Range. 
At7A.M 
At2P. M 
At 9 P. M 
Whole month .... 
Second average . . . 
44.32° 
57.39° 
47.26° 
49.68° 
49.06° 
24° 
40° 
30° 
24° 
24° 
60° 
79° 
66° 
79° 
79° 
36° 
39° 
36° 
55° 
55° 
Last 21 Octobers . . . 
Second average . . . 
50.50° 
49.94° 
I 46.60° 
j in 1888. 
46.01° 
56.16° ( 
in 1879. S 
55.88° 
9.56° 
9.37' 
The lowest point reached by the thermometer 
the last month was 24°, on the 29th ; the highest, 
79°, on the 4th. The 23d and 29th were the cold- 
est days, each averaging 36. .3.3° ; the 4th was the 
warmest daj', at 67.66°. The entire month was 
.84° below the average for the last (nventy-one 
Octobers. The first frost of the season with me 
— a very light one — was on the 12th. Other frosts 
occurred on the 23d and 2.5th, and a severe one on 
the 29th, previous to which the green foliage of 
the leaves had but slightly changed. 
SKY. 
The face of the sky, in 93 observations, gave 43 
fair, 19 cloudy, 22 overcast, 8 rainy, and 1 snowy, 
— a percentage of 46.2 fair. The average fair for 
the last twenty-one Octobers has been 55 per 
cent., with extremes of 38.7 in 1890, and 73.1 in 
1874, — showing the last month to have been un- 
usually cloudy. It is a singular record that the 
ten years from 1881 to 1890, inclusive, averaged 
only 49 per cent, fair, while the previous ten 
years, from 1871 to 1880, averaged 61.8 — an excess 
of 12.8 per cent. Is it possible that our bright 
October is losing some of its beauty f 
PRECIPITATION. 
The amount the last month, including about 
two inches of melted snow, was 4.35 inches, which 
fell principally on five occasions, well distributed. 
The average amount the last twenty-three Octo- 
bers has been 4.26 inches, with the wide extremes 
of .75 inch in 1874, and 13.20 inches in 1869. 
This is the third instance in twenty-three years 
that we have had snow in this locality in Octo- 
ber. It was a novel sight on the morning of the 
23d to see the moist white snow adhering to the 
green leaves on every side, bending the trees 
nearly as much as the abundant fruit had done 
just before, and often breaking the branches. 
The amount of precipitation since January 1 has 
been 48.22 inches, while the average for this pe- 
riod has been only 39.64, — giving an excess this 
year of 8.58 inches. 
PRESSURE. 
The average pressure the past month was 30.013 
inches, with extremes of 29.59 on the 8th, and 
30.50 on the 12th, — a range of .91 inch. The mean 
for the last eighteen Octobers has been 29.987 
inches, with extremes of 29.826 in 1875, and 30.109 
in 1886, — a range of .283 inch. The mean daily 
movement the last month was .216 inch, w hile this 
average the past eighteen Octobers has been .168 
inch, with extremes of .113 and .216. Thus the 
daily movement the past month was greater than 
in any October for eighteen years. The largest 
daily movements the last month were .69 inch on 
the 8th, and .45 on the 13th. 
vriNDS. 
The average direction of the wind the past 
month was W. 64° 6' N., while the mean for the 
last twenty-two Octobers has been only W. 19° 
14' N., with extremes of W. 35° 15' S. in 1880, and 
W. 82° 25' N. in 1883,— a range of 117° 40', or 
more than ten points of the compass. The winds 
have been nearly 45° more northerly than usual. 
The relative progressive distance travelled the 
last month was 38.92 units, and during the last 
twenty-two Octobers 732 such units, — showing 
less easterly winds the last month than usual. 
D. W. 
Natick, Nov. 5, 1891. 
[Specially Computed for Populak Science News.] 
ASTRONOMICAL PHENOMENA FOR 
DECEMBER, 1891. 
The sun reaches its greatest southern declina- 
tion on December 21 at 11 P. M., and winter be- 
gins at that time. Mercury is an evening star 
until the end of the month. It reaches its great- 
est eastern elongation on December 11, when it is 
more than 20° distant from the sun. As it is, 
however, somewhat farther south, the conditions 
are not very favorable for visibility. Probably it 
can be seen on a very clear evening, just after 
sunset, during the first third of the month. After 
elongation it moves rapidly toward the sun, and 
reaches inferior conjunction on December 28. 
Venus is also an evening star, and is quite near 
Mercury during the first few days of the month. 
Both planets are then moving eastward, the latter 
much more rapidly, and it passes the former on 
the morning of December 5, the nearest approach 
being a little more than 1°. Venus is increasing 
its distance from the sun, and by the end of the 
month sets about two hours later. Mars rises a 
little after 3 A. M. It is gradually approaching 
us and growing brighter, but will not be very 
conspicuous for some months. It will be occulted 
by the moon on December 26, but the phenome- 
non will not occur until after daylight in the 
United States. Jupiter is still the most promi- 
