THE MEDITERRANEAN NATURALIST 
359 
more abundant in dry soil than in wet. In dry 
regions simple irrigation yields .a bountiful harvest 
while moist soil is quickly exhausted. 
“T^ATURAL Science” for March has, as usual, a 
series of most interesting and valuable con- 
tributions among which we note “The Micleus in 
some Unicellular Organisms by Rev. W. H. Dal- 
linger, L.L.D., F.R.S. “Are Great Ocean Depths 
Permanent /” by Professor Edward Suess Ph., D. 
“The Origin and Classification of Islands” by 
A. J. Jukes — Browne B. A., F. G. S. “Biological 
Theories” by 0. II. Hurst Ph. D., Recent Obser- 
vations on Fertilisation and Hybridity in Plants 
“by A. W. Bonnet M. A., F. L. S. and “Animal 
Temperature” by M. S. Pembrey M. A., M. B. 
C ITUATED as the Maltese Islands are in the 
middle of one of the most, interesting regions 
in the w >rld it is but natural that they should, in 
common with the countries around them, be much 
resorted to by curiosity hunters. At the present 
time a thriving, trade is being done in reputed 
Phoenician, Greek, and Roman relics, in Lace, in 
Filigree work, and in Maltese Dogs. 
~0”UNDREDS of dogs of more or less dor.Mful 
origin annually change hands at prmes vary- 
ing from a few shillings to as many pounds apiece. 
That the Maltese dog is now extinct is, however, a 
fact which appears tp trouble nei tber seller nor buyer 
at the time of the bargain driving. Aristotle was 
one at the first writers who drew attention to the 
remark ible breed of dogs for which the Maltese 
Islands weres > long famous, and be notes that they 
were specially sought after by Greek and Roman 
la lie s on account of their beautifiT.lv proportioned 
forms and their diminutive size. 
A stuffed specimen of one of these dogs is stiil 
preserved in the Malta University Museum. It 
has long silken hair and measures 5 inches in 
length, and 3 inches in height. 
VIDENCE that a copper age existed before 
the discovery of bronze has been found by 
M. Berthellot, A piece of copper from Mesopo- 
tamia, taken from ruins more ancient than even 
those of Balylon, proves to be free from both tin 
and zinc; while a piece < f a metallic scepter, sup- 
posed to have belonged to a Pharaoh in Egypt 
some 3500 years B. (J., is also shown to be nearly 
pure copper. — — 
npHE idea that the. oak and certain other 
trees are particularly subject to destruction 
by lightning, while the laurel and others are 
tree from danger, has been investigated by P. 
Jenesco. The conclusion is reached that no trees 
are exempt from risk. Trees containing oils are 
less liable to be struck, those with most oil 
being best protected; while lightning seems to 
prefer trees containing much starch, and those 
which have little oil in summer. Dead limbs of 
either starch or oil containing trees are especially 
liable to be struck. Neither the quantity of water 
contained in the tree nor the character of the soil 
in which it stands appears to have any influence. 
CERTAIN speculations make it appear, ac- 
Ab cording to M. Raoul Pictet, that chemical 
affinity must be absent at the temperature of 
absolute zero— that is, 5750 C. below the mel- 
ting point of 'ice. Experiment confirms this 
belief. At about 150° below zero, chemical action 
has be ;n found to be weak, sulphuric and ni- 
tric acids having no efl'ect upon potash, and 
potassium remaining unchanged in oxygen. En- 
tirely new combinations,, moreover, have been 
effected by the action of the electric spark 
on substances maintained at that temperature. 
AySTHY the moon-unlike most globes known 
* ' to us in space — should have no atmos- 
phere has long been a perplexing question. Sir 
Robert Ball, of Cambridge University, states 
that this may now be explained as a necessity 
consequence of the kinetic theory of gases, this 
theory tea -lies that any gas is composed of mole- 
cules in very rapid motion. The molecules of 
of hydrogen are the most active of all, and at 
ordinary temperatures they move at an average 
rate of more than 6000 feet per second. The 
average motion of molecules of oxygen and 
nitrogen is much less, but individual molecu- 
les frequently attain velocities greatly in ex- 
cess of the average. This latter fact is impor- 
tant. The mass and dimensions of the moon 
are such that if a body were projected from 
it at the rate of about a mile per second lunar 
attraction would be overcome, and the body 
would not return. With, an atmosphere of oxy- 
gen and nitrogen, the moon would by its at- 
traction keep the molecules when at average 
velocity. But occasionally molecules in the upper 
