359° 
NATURE 
[FEBRUARY II, 1897 
reverse Franklin’s historic kite experiment, and instead of draw- 
ing electricity from the clouds, to electrify a balloon by means 
ofa conducting cable connected witha dynamo, In this way, 
the writer maintains, the rainfall can be increased, or, possibly, 
even decreased, at pleasure. 
IN an article entitled “‘ Fog Possibilities,” Mr. A. McAdie, 
in Harper's Monthly Magazine for January, refers to the 
possibility of dispelling fog from crowded thoroughfares. The 
experiments of Aitken and others have shown the close relation- 
ship between fog, cloud, or haze, and the number of dust 
particles in the air. If we can remove the dust from the air, 
we remove the nuclei of condensation. Dr. Lodge has pointed 
out various methods by which this can be effected in laboratory 
experiments, the most successful of which is electrification. 
The author considers that by this means the fog can probably 
be dissipated and the air clarified. The supply of fog may be 
such that there would be little appreciable diminution, but as a 
rule the fog is localised and has well-marked limits. 
AN important series of experiments on the absorption of ultra- 
violet light by crystals, has been conducted at Geneva by M. V. 
Agafonoff, of St. Petersburg (Archives des Sczences physiques et 
naturelles, iv. 2). Among the 100 different crystalline substances 
observed, only two were found to exhibit differences of absorption 
according to the direction of polarisation of the light ; these were 
tourmaline and hemimellitic acid, which gave different absorp- 
tion spectra for the ordinary and extraordinary rays of a doubly- 
refracting prism. Isolated absorption bands are rare, and were 
only found in the seven following substances ; sulphate of mag- 
nesium, sulphate of ammonium and nickel, ammoniacal alum, 
nitrate of nickel, nitrate of potassium, dithionate of barium, and 
anthraquinone. The thickness of the section seems to have 
very little influence on the limit of wave-length at which absorp- 
tion commences. The powerful absorption of organic, as com- 
pared with inorganic compounds, suggests that highly complex 
molecules are more absorbent of ultra-violet light than simple 
molecules; and, if this be the case, the property may afford a 
test of the relative complexity of different compounds. 
From Mr. William Barlow we have received a reprint of his 
important communication to the J/neralogical Magazine, en- 
titled ‘* On Homogeneous Structures and the Symmetrical Par- 
titioning of them, with Application to Crystals.” The author 
gives a new definition of homogeneous structure, and describes a 
method of realising, in a concrete form, the kind of repetition 
in space which constitutes homogeneity of structure. The total 
number of types, all of which can be represented in this way, 
is 230, this being the number of typical point systems described 
by Federow and Schonflies, derived by their extension of 
Sohncke’s methods. These all fall into the thirty-two classes 
of crystalline symmetry. The author gives reasons for reject- 
ng Fedorow’s arguments in support of his recent attempt to 
select from among the types of homogeneous structure those 
which are possible for crystals, and he shows the possibility of 
so classifying all the conceivable ways of symmetrically par- 
titioning all the types of homogeneous structure as to avoid all 
reference to the nature of the cell faces. Among the reasons 
for undertaking this classification, the chief one is the relation 
of symmetrical partitioning to certain stereo-chemical and other 
facts. 
THE latest evidence as to the occurrence of Man in the 
Glacial Period has just appeared in the American Geologist 
(vol. xviii. p. 302), where Dr. E. W. Claypole records the 
finding of a grooved stone axe at a depth of 22 feet in the 
drift of North-central Ohio. The axe, which was partially im- 
bedded in boulder clay, lay in a bed of coarse gravel 1 foot in 
thickness ; above this was a bed of silt, 13 feet in thickness, 
NO. 1424, VOL. 55] 
and very tough below ; interbedded in this were streaks of sand ; 
finally, there were superimposed 8 feet of clay. Dr. Claypole 
regards these beds as having been ‘“ the deposits of the torrents 
of water and the still pools which characterise the flow from the 
front of a glacier in a flat country” ; he supports his statement 
by a description of the district, and he also enters into the dona 
fides of the discoverer of the implement. The axe was made 
of a hard, banded green slate, but it was oxidised throughout, 
owing to the sulphureous character of the water in the gravel ; 
the concentric lines of colour (limonite stains), parallel to the 
contour of the implement, prove that the change has taken place 
since it was fashioned by its Neolithic maker, and the rotten 
state of the stone shows that it must have been imbedded in the 
gravel fora very longtime. It is always a difficult matter to 
sift the evidence of such finds, but this one appears to be 
worthy of the critical examination of American geologists and 
archeeOlogists. 
FossiL bones of the Pleistocene age have been brought to the 
Academy of Sciences of Philadelphia from Port Kennedy, 
Montgomery County, Pa. The fossil deposit seems almost un- 
limited ; and while it contains no complete skeletons, it is, in 
many respects, the richest ever discovered. Bones form fully 
one-third of the material in the giant fissure, but most of them 
are so crushed and distorted as to be of no value. About forty 
distinct varieties of animals have been found in the mass. 
PRESIDENT Davip S. JoRDAN, of Leland Stanford Junior 
University, Commissioner to investigate the condition of the fur 
seal, recommends, in his report to the;Secretary of the Treasury, 
that the open season for the killing of females be abolished, to 
keep the Pribilof herd intact. He estimates the number of 
seals killed last summer as 440,000, About 27,000 pups died 
of starvation, and pelagic sealing caused the death of about 
30,000. Since pelagic sealing began, more than 600,000 fur 
seals have been taken in the North Pacific and in Bering Sea, 
taking into account only those whose skins were brought to 
market. Many more were shot or speared, and lost. The 
number reported means the death of 400,000 females, the 
starving of 300,000 pups, and the destruction of 400,000 pups 
unborn. 
THE January number of the Quarterly Journal of Microscopical 
Scéence contains only two memoirs, both of which are more 
than usually suggestive and interesting. Miss Lily Huie 
describes the results of a very precise and systematic investiga- 
tion of the changes which take place in the protoplasm and 
nucleus of the gland-cells in the tentacles of the sun-dew 
Drosera rotundifolia, after the feeding of the leaf with pieces of 
white of egg. The first effect of the contact of the food appears 
to be the discharge of secretion from the gland cells. The 
secretion is formed at the expense of the basophile cytoplasm, 
which is stained by alkaline stains. The nucleus produces new 
cytoplasm of the same kind, by absorbing nutriment, converting 
it, and then ‘‘excreting” it. In this process the nuclear 
chromation takes the form of V-shaped chromosomes, and the 
nucleolus grows smaller and almost disappears. The nuclear 
chromation increases in bulk. Thus the changes which occur 
resemble those to which so much attention has been directed in 
mitosis or the division of the cell, and the conclusion is drawn 
that these changes indicate great activity in the nuclear organs, 
and are not exclusively characteristic of cell-division. 
THE second paper in the January Q. /. JZ. S. is by Messrs. 
J. T. Wilson and J. P. Hill, of the University of Sydney, 
New South Wales, on the development and succession of the 
teeth in the marsupial Perame/es, and in other marsupials. 
It is well known that only one tooth, the last of the pre- 
molars, is observed to be shed and replaced by a successor in 
