March 10, 1870] 
LNT OORIE: 
481 
short sketch of his life precedes Prof. Oersted’s memoir, 
the substance of which had been already published in a 
scientific journal of Copenhagen. 
The principal novel feature in Prof. Oersted’s arrange- 
ment of the numerous species of oak—a genus including 
about 160 species in the Old World, and 120 in the New, 
—consists in the importance, for classificatory purposes, 
attributed to the form of the style and stigmatic surface. 
Upon these organs the sub-genera are chiefly based. We 
have had no opportunity of testing these characters, which 
it is unfortunate were not investigated by M. Alph. de 
Candolle, when preparing the Cupulifere for the “ Pro- 
dromus,” published in 1864. The omission of a Species- 
Index to the genus Qwercus in the “ Prodromus,” makes 
it very tedious to ascertain how many of Liebmann’s 
species are included in that work. Let us express the 
hope that in the final volume of this great work, yet to be 
published, we may be spared this annoyance in the case 
of the larger genera. D.O. 
LETTERS TO THE EDITOR 
[ The Editor does not hold himself responsible for opinions expressed 
by his Correspondents. No notice is taken of anonymous 
communications. | 
Prismatic Structure in Ice 
OF late years attention has not unfrequently been called to this 
singular structure in ice, of which a number of instances are col- 
lected by the Rey. G. F. Browne, in his valuable book on the 
**Ice Caves of France and Switzerland” (chap. xviii.) In 
August, 1865, I had the opportunity of examining in his com- 
pany some of these curious caverns ; and since then have been 
on the look out for other instances of this structure. In January, 
1867, I found it very well exhibited on a pond in Cambridge, an 
account of which may be found in the Proceedings of the Cam- 
bridge Philosophical Society, Part IV. and (more briefly) in my 
** Alpine Regions,” pp. 94, 334. I again saw it last summer in 
a block of river or lake ice, which was brought on board a 
steamer at Christiansand (Norway) from an ice house. This 
block was about 8 inches thick. The prisms were rather irre- 
gular in form, the area of their ends varying from about a quarter 
of a square inch to one square inch, the sides being usually five 
or six in number. The prisms were at right angles to the planes 
of freezing, which were well marked. 
These two were the only casesin which, from the first date until 
a few months back, I had succeeded in finding this prismatic 
structure clearly exhibited, but the present winter has proved 
very favourable to its development. I have seen it several times ; 
in fact, after every severe frost ; and under circumstances which 
have led me to suspect that I have often overlooked it on former 
occasions. In almost all the cases which I have lately noticed, 
the prisms were small, the area of their ends being generally 
about one-sixteenth of aninch. Hence, frequently the structure 
could not be detected without very close examination ; as it was 
masked on the surface exposed to the air by the usual layer of 
disintegrating ice ; and even when the under and unmelted side 
of a slab was examined, it had to be partly dried, before the 
delicate reticulation produced by the jointed structure could be 
observed by allowing the light to fall obliquely on it. The 
simplest mode of detecting it was to break the slab across, when 
instead of the usual conchoidal fracture of ice, a columnar 
structure was distinctly shown. Not unfrequently the first hint 
of its presence was given by the presence of a number of 
small holes in the under side of the slab. These, of course, were 
formed by water, which had trickled down from the thawing 
upper surface between the angles of the prisms, and had thus 
drilled itself a small tube. In one case—during a frost after a 
partial thaw—I found the structure mapped out, as it were, 
on the surface of the ice, but quite obliterated internally, 
except where some vertical lines of air bubbles marked the 
position of a tube or wider joint. In one of the cases above 
described, I totally obliterated the internal columnar structure 
by placing the ice in a freezing bath. I have often looked 
for, but never found it in glacier ice. I am therefore inclined 
to think that, though the large and strongly marked prisms are 
of comparatively rare occurrence, this finer structure may be 
found, if looked for, in every tolerably gradual thaw. Repeated 
examination has also convinced me that the structure has no 
immediate connexion with the hexagonal form of the ice crys- 
tals; the angles of the prisms are too irregular and variable 
to admit of this explanation. Their sides, however, so far as 
I have seen, are always at right angles to the surface of 
freezing, and are best developed when the temperature of the 
neighbouring air for a considerable time does not differ much 
from 32° Fahr. I therefore consider the structure to be pro- 
duced by contraction in the ice as it approaches the melting 
point, and so to be analogous to the columnar structure in 
basalt, though due to a rise instead of to a fall in temperature. 
St. John’s College, Cambridge T. G, BonNEy 
A Probable Cause of Malaria 
SINCE men of science, such as Dr. Carpenter, Jeffreys, and 
Wyville Thomson, have proved by repeated and well-conducted 
experiments that there is life in the ocean, * that there are moving, 
sensible, living creatures, of nearly every description, in its 
deepest recesses, it seems rather an idle question, “de land 
caprina,” which has been raised lately about their manner of 
living there ; how they get their food where no plant of any 
description has ever grown; whether they take in their food by 
intussusception with a mouth, or by that kind of oozing-in-and- 
out styled endosmose and exosmose, or by any other kind of 
absorption, suiting the glair-like sarcodic stuff which the eozoon 
of old was made up of, and whichis still at work in building, roll 
upon roll, the myriads and myriads of microscopic Globigerine.t 
Yet these seemingly idle questions when treated by men of science 
and of experience may become the source of discoveries far 
greater and more important perhaps than they anticipate. 
Thus it is that the indefatigable Italian diatomist, Count Cas- 
tracane, after having proved the very abundant growth of his 
puny frotégés in the brackish waters of the Mavemme and 
faludi pontine, did not esteem it a bootless task to search for 
what they live upon, and also why they suddenly die away nearly 
all at once, 
Such is the subject of a recent memoir which he has lately 
presented to the Roman Academy Dei Zincei, of which he is one 
of the most activemembers. After insisting upon the necessity 
of mastering the subject more thoroughly before attempting any 
new revision or classification of the diatoms, showing the system 
he had followed himself, and the results he had obtained, 
especially during the last year in making the round of the Istrian 
peninsula, taking his headquarters at Trieste and Pirano most 
particularly, where he gathered a rich harvest of very important 
materials for future study, he goes on to state that nothing 
is so fatal to the life of marine or even brackish water diatoms 
as a sprinkling of pure fresh water. This he proved by repeated 
and carefully performed experiments. From this fact he comes 
to the very probable conclusion that the sudden dying away of 
myriads of diatoms, besides, perhaps, myriads of other living 
creatures, during the rainy season might be, if not the only, 
at least one of the most efficient causes of malaria. 
Before concluding this letter I wish to call the attention of the 
British scientific public ;to another Italian naturalist, M. A. 
Acorti, Professor of Natural History at the R. Gymnasium of 
Trieste, who has made the Adriatic a special subject of his 
studies, and is now engaged in the publication of the diatoms of 
that sea. “ The sketching of his figures,” says Count Castracane, 
“is of such beauty that I never saw anything better of the 
kind, and I hope they will be soon published that I may pur- 
chase them,” J. GAGLIARDI 
* We have now plenty of living Protozoa, Radiata, Annulosa, Mollusca, 
and even of Vertebrata aéyssicole. 
+ On account of the porous substance, which is a speciality of those won- 
derful beings, Johnstone has classed them under the significant name of 
Amorphozoa porifera. ‘ 
t After the late remarks on this subject by Prof. Wyville Thomson in 
NATuRE, it is curious to see the manner in which a Fellow of the Royal 
Society of the last century (John Ray) treated “the various ways of ex- 
tracting the nutritious juice out of the aliment in several kinds of creatures. 
For oviparous quadrupeds,” he says, ‘‘as chameleons, lizards, frogs, as also 
in all sorts of serpents” (there were, of course, no protozoa known in his time), 
“there is no mastication or comminution of the meat either in mouth or sto- 
mach ; but as they swallow insects or other animals whole, so they void 
their skins unbroken, having a heat or spirits, powerful enough to extract the 
juice they have need of, without breaking that which contains it: as the 
arisian Academists tell us. 1” (subjoins Ray candidly) ‘‘ cannot myself war- 
rant the truth of the observation in all. I haye taken two entire adult mice 
out of the stomach of an adder, whose neck was not bigger than my little 
finger. These creatures, I say, draw out the juice of what they swallow 
without any comminution, or so much as breaking the skin ; even as it is seen 
that the juice of grapes is drawn as well from the rape (cluster), where they 
remain whole, as from the vat, where they are bruised, to borrow the Parisian 
philosopher's similitude,”” 
