426 
NATURE 
[ Sept. 28, 1871 

seed, but is the result of some electrical action producing them 
spontaneously. The late Duke of Portland used to say they need 
not sow white clover where bones were used freely ; and where 
the pure white lime is used, clovers are seen without sowing 
seed. Also, if, asmay be seen any season on the roads of Derby- 
shire, where the roads are repaired with white limestone, the 
clovers are present by the side of the wheel-tracks, ‘The same 
may be seen on laying land down to permanent grass. Use farm- 
yard manures, and the coarser grasses are seen; use road- 
scrapings and compost, and the finer grasses are sure to come. 
The charlock is an unwelcome visitor ; but its removal in corn 
crops is often worse than the evil itself. ‘Let both grow 
together till the time of harvest.’ The seed has more value 
than some suppose, and when crushed will be found a good tonic. 
Nothing is given to us in vain.” 
Comment in this case also is needless. One hardly knows 
which most to admire in this rich paragraph ; the independence 
of the trammels of the ordinary rules of syntax displayed by the 
writer ; the teleological moral drawn at the end ; or the contempt 
for science manifested in the assertion of the possibility of so 
highly- organised a plant as the charlock arising ‘* spontaneously ’ 
in the ground. When such lamentable ignorance of the very 
elements of science is displayed by those who should be the 
leaders, what can we expect from the farmers themselves? Well 
may we exclaim, Qzs docebit ipsos doctores ! 
ALFRED W, BENNETT 
London, Sep. 23 


IGE FEEASS 
8 water flea, ' Daphne pulex, is a well-known inhabi- 
tant of rivers and fresh-water lakes, and, being dis- 
tinctly visible to the naked eye, often attracts the attention 
of water drinkers. Though a harmless crustacean, this 
little creature not only excited great interest in parliamen- | 
tary committees during the last session, but exercised a 
very powerful influence over the choice of a water supply 
for the northern capital of Great Britain. 
if known at all, is certainly less celebrated, and probably 
by no means likely to be so potent in its parliamentary 
influence ; nevertheless a short account of it may not be 
wholly uninteresting to the readers of NATURE. 
During a recent ramble upon the Morteratsch Glacier, | 
I turned over some of the isolated stones which lie upon | 
its surface partially imbedded in the ice ; under many of 
them I found hundreds of a minute jet black insect, which 
jumped many times its own length at a single spring, in a 
manner somewhat resembling the performance of a com- 
mon flea.* The ice flea is about one-twelfth of an inch 
long. 
six legs, supporting a body obscurely jointed like that of a 
bee, and furnished with two jointed antennze. The total 
length of the insect appeared to be about six times its 
thickness, the antennz being about one-fourth as long as 
the body. The insects were not found under every stone, 
they generally occurred under flattish fragments of rock, 
presenting a surface of about a square foot, and having a 
thickness of from 2 to 4 inches. Stones of this size are 
sufficiently warmed by the sun’s rays to melt the ice be- 
neath them more rapidly than it is liquefied by the direct 
solar beams. A surface of rock absorbs luminous thermal 
rays better than does a surface of comparatively white 
ice, and it transmits these rays to the ice beneath it, parily 
by conduction and partly by radiation from its under sur- 
face. 
into the ice, forming for itself a kind of basin. Sometimes 
these cavities are watertight, and then any space between 
the stone andthe walls of its basin are filled with water 
derived from the melting ice. Under such conditions I 
have never found any fleas beneath the stone. But occa- 
sionally the ice basin is drained, and it was under stones 
_ * My friend Prof. Eschenburg, of Ziirich, had previously observed these 
insects on the Morteratsch Glacier, and it was his verbal account of them 
that led me to search for them. 
The ice flea, || 

| sible for us to come to any definite conclusions. 

resting in such comparatively dry basins that the insects 
were found. In all cases nearly the whole of the fleas 
were found upon the ice, very few being attached to the 
stones. They were grouped together in shoals, so that 
probably forty or fifty of them frequently rested upon a 
single square inch of ice. On removing the stones, the 
insects were very lively, but this might be owing to their 
sudden transition from comparative darkness to direct 
sunlight 
I saw no indications of food cf any kind beneath the 
stones, indeed these insects must have a struggle for 
existence of a most severe character. Livingin an atmo- 
sphere the temperature of which never rises above the 
freezing point, they must be continually exposed to inun- 
dations during the day by the stoppage of the drainage of 
the ice basin, whilst on clear nights severe frosts frequently 
threaten them with an icy grave. Again, during the day 
the roof of their habitation is, as it were, continually falling 
in upon them, and thus constantly exposing them to the 
risk of being crushed to death ; for, as the ice melts be- 
neath the stone, the latter is continually changing its 
points of support. It may be, however, that the crystalline 
structure of the ice causes it to melt with a corrugated 
surface, which provides everywhere valleys of sufficient 
depth to protect the fleas from destruction by the fall of 
the superincumbent mass of rock. We have also not to 
search far for a possible source of food. The cold of the 
glacier benumbs and kills thousands of insects which 
alight upon its surface, and bees, wasps, flies, and moths 
are frequently seen dead upon the ice. Then there is the 
so-called “red snow,” and other allied organisms of similar 
habits, which may perhaps minister to the wants of this 
singular insect. Is the ice flea, like its irritating cousin, 
a nocturnal predatory insect, and does it issue from its 
dangerous abode at nightfall in search of frozen bees 
and butterflies? Perhaps some of the entomological 
readers of NATURE may be already acquainted with this 
animal, and be able to supply further information re- 
specting it. 
FE. FRANKLAND 

REMARKS ON PROF. 
CLASSIFICA TION 
CRYPTOGAMS 
WILLIAMSON'S NEW 
OF THE VASCULAR 
N discussing the points at issue between Prof. Wil- 
liamson and myself, it will be necessary for me to 
: | say a few words on stems in general, because we evidently 
Viewed through a pocket lens, it was seen to have 
have very different views of the construction of stems ; 
and until we thoroughly understand each other, it is impos- 
Ina 
young dicotyledonous stem (see Oliver's “ Lessons,” p. 112, 
fig. 67) we find three things : a quantity of cellular tissue 
surrounded by an epidermis, and near the centre a series 
of young fibro-vascular bundles. As growth goes on, these 
separate bundles coalesce and form a central cylinder of 
united fibro-vascular bundles. These bundles leave a 
portion of the cellular tissue in the middle of the stem, 
which becomes the pith. Outside the fibro-vascular bun- 
dles we have also a small quantity of the cellular tissue, 
but it soon becomes to a great extent inseparable from the 
sub-epidermal cells. Other portions of the cellular 
i c | tissue remain between the united fibro-vascular bundles, 
The stone thus melts its way an inch or two deep | 
and form the medullary rays. In many stems and in 
most roots these rays are wanting, and the cellular tissue 
would therefore be divided into two portions by the united 
bundles. Each fibro-vascular bundle consists of two 
portions, which are separated by a layer of cells capable 
of division, the cambium. On the inner side of the 
cambium cells we have in general spiral vessels, porous 
vessels, and wood cells, while on the outer side we have 
the soft bast and bast fibres. The epidermis is soon thrown 
off in many cases, and is replaced by layers of cork-cells 
