126 
NATURE 
[ Fune 11, 1885 
virtues the Kola nut is considered to have a great future 
before it in European commerce, and is consequently 
strongly recommended to the notice of planters in our 
colonies for extensive cultivation. With regard to the 
preservation of the germinating properties of the seeds, 
Mr. Christy says he has received them in good condition, 
both in baskets and barrels lined with the leathery leaves 
of a tree known as the “bal tree.” Some received in 
dry loam arrived as fresh as when they were gathered, 
and of some that arrived eighteen months since, the bulk 
is stated to be perfectly fresh and retaining still their 
beautiful red colour. 
From a list of fifteen species of AZyristica, the fruits or 
seeds of which are described, the value of the nutmeg 
genus is shown, especially as oil seeds. Seeds new to 
commerce are frequently arriving in the Liverpool and 
London markets, intended for the expression of oil and 
for the preparation of oil cake. Such seeds are of a very 
varied character and belong to widely different natural 
orders, and not long since those of ALyréstica surinam- 
ensts came into Liverpool under the name of African nuts. 
Upon analysis they were found to contain a large quantity 
of solid oil or fat with an agreeable taste, and but little, if 
any, odour, and when fairly pure it is said to resemble 
cocoa butter, 
Amongst other important economic plants or drugs 
mentioned are the Coca (Evythroxylon coca), the medical 
effects of which have attracted so much attention of late ; 
the Jamaica Chewstick (Gouvania domingensis), which, it 
is stated, “ has recently been introduced into this country 
by one of our leading London dentists for use in tooth 
powder and mouth wash,” and also in the form of a fluid 
extract as a garele for relaxed throat. 
Of Papaine, the active principle of the Papaw (Carica 
papaya), some interesting records are given regarding its 
effects in treatment of diphtheria, croup, indigestion, 
dyspepsia, &c. 
LETTERS TO THE EDITOR 
[Zhe Editor does not hold himself responsible for opinions expressed 
by his correspondents. Neither can he undertake to return, 
or lo correspond with the writers of, rejected manuscripts. 
No notice is taken of anonymous communications. : 
[The Editor urgently requests correspondents to keep their le:ters 
as short as possible, The pressure on his space is so great 
that it ts impossible otherwise to insure the appearance even 
of communications containing interesting and novel facts.] 
Ocular After-Images and Lightning 
In reply to Mr. Shelford Bidwell’s query whether the quiver 
of the lightning flash is a purely subjective phenomenon or not, I 
send the following extract from my note-book, made October, 
1873:—‘‘A flash of lightning consists of several separate 
flashes all occurring within a fraction of a second of each other. 
There was a very severe thunder storm at night, the thunder 
almost continuous. Drawing the curtain across the window so 
as to expose only a narrow slit of skylight, I observed this slit in 
the looking-glass which I kept moving rapidly backwards and 
forwards on its axis. Whenever a flash occurred, several images 
of the slit appeared, showing that there wer several successive 
illuminations of the slit.”” 
This was not the result I had expected, the experiment having 
been suggested to my mind in consequence of some experiments 
I had been making on the phenomenon of recurrent vision. 
The results of these experiments were published in the P42’. 
Mag., December (supplement), 1872. One object of my experi- 
ments was to determine in what way the colour of the recurrent 
image depends upon the colour of the light producing it. By 
using a sliding shutter and a small window covered with different 
coloured glasses, I found that the colour of the recurrent image 
tends to be of a tint complementary to that of the light causing 
it, being, however, in all cases bluer than the complementary 
tint. I add the following extract from my paper:—‘‘A re 
current image of an object may be produced without any appar- 
atus whatever. To do this, place the right hand over the eyes 
so that the palm of the hand covers the right eye, and the fingers 
the left eye. Ifthe middle finger be then raised for a moment, 
so as to admit light for as short a time as possible into the eye, 
a recurrent image of any light-coloured object held against a 
dark background may be seen. The effect is much better seen 
by twilight or gaslight than in full daylight. This method of 
producing a recurrent image is, however, much inferior to that in 
which a sliding shutter is used, owing probably to the illumination 
IN your issue for April 30 (vol. xxxi. p. 601) is an account of 
a quinquefoliate strawberry. In the garden of the New York 
Agricultural Experiment Station at Geneva we have some second 
year seedling strawberries, some of which are bearing three, 
four, and five leaflets on the same plant, the leaves all large and 
perfect. We have other plants in which the two extra leaves 
are borne half way down the petiole, and which attain fair size, 
and yet others where these stipulary-like appendages are reduced 
to hair-like bracts. The variety of strawberry introduced under 
the name ‘‘ Mrs. Garfield” frequently has these bract-like 
appendages. While speaking of the strawberry, I would remark 
that seedling strawberries very frequently are unifoliate during 
their early growth, and it appears as if Duchesne’s Fragaria 
monophylla may be regarded as an instance of arrested develop- 
ment in one of these one-leaved younglings. 
E. Lewis STURTEVANT 
New York Agricultural Experiment Station, 
Geneva, N.Y., May 28 
OBSERVATIONS OF THE TEMPERATURE OF 
THE SEA AND Aik, MADE DURING A 
VOYAGE FROM ENGLAND TO THE RIVER 
(PICA TEE WIN, TUES SuSE BN alee 
Beas obliged to proceed to South America at the 
beginning of this year, I took with me a thermo- 
meter and a hydrometer in order, if circumstances were — 
favourable, to provide myself with occupation during the — 
somewhat long and monotonous voyage. Thanks to the — 
kindness and courtesy of Capt. Brown, of the s.s. Lezénztz, . 
; 
; 
: 
of the retina not being sufficiently instantaneous. 
Cheltenham College, June 6 A. S. Davis 
A Quinquefoliate Strawberry 
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F 
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who took a lively interest, and assisted me greatly in 
carrying out my observations, the voyage was neither 
long nor tedious. j 
The Lezénitz sailed from Southampton on January 16, 
1885, and made the passage direct, without touching at 
intermediate ports, to Monte Video, where she arrived on 
February 8, after a very favourable voyage. The route © 
lay through the most interesting meteorological districts 
of the Atlantic, and my principal object at starting was to 
make as many observations of the temperature and the 
density of the surface-water along the route as possible. 
With these I combined observations of the temperature 
of the air, and frequently also of the wet-bulb thermo- — 
meter. Observations were begun on January 21 in 
lat. 34° N., and continued up to the morning of arrival 
in the River Plate. 
I have put together the simultaneous observations of 
the temperature of the air and the water with those of the © 
wet-bulb thermometer, as they possess some interest of | 
their own ; the observations of density are kept for a — 
future opportunity, as the reductions in connection with © 
them are not quite finished. | 
The thermometer used for all the observations was— 
divided into simple degrees of the Centigrade scale, and 
was of the ordinary form of German manufacture, with a 
paper scale. The degrees were 1°6 mm. apart, so that 
there was no difficulty in estimating tenths of a degree. 
Its zero was verified on board by immersing it in pounded ~ 
ice, and found correct. The ice was well pounded in a 
clean towel, and a soda-water tumbler filled with it ; the 
thermometer was then thrust into it and allowed to remain 
till sufficient ice had melted to fill up the interstices, pro- 
ducing a perfect magma of ice and water down to the | 
