202 
THE MEDITERRANEAN NATURALIST 
Pinna are found in Malta, some of them 
common in the harbours within reach of a 
boat or a pole hook. They project from 
the mud amongst the Zostera roots to which 
they are attached by their silken cable. Of 
this silk, which is of fine texture, but heavy, 
I have seen gloves made!' 
Street Microbes. — The dust of the 
streets of Naples has been the subject of 
an elaborate investigation by Dr. Luigi 
Manfredi, who reveals startling possibilities 
of evil. The microbes of all kinds found 
in the dust averaged' 7 01,521, 000 per gram- 
me, though in the cleanest and least trave- 
led streets the average number was only 
10,000,000 per gramme, while in the busiest 
thoroughfares it rose to 1,000,000,000, and 
in some of the dirtiest streets to the enor- 
mous figure of 5,000,000,000 per gramme. 
Many of these organisms were those of 
disease, and the unhealthiness of the street 
or quarter was directly proportional to the 
number of microbes in the dust. The in- 
fective power of the dust was tested, with 
positive results in 73 per cent of the expe- 
riments, suppuration, tetanus, tuberculosis, 
blooa-poisoning, etc., being produced in 
dust-inoculated guinea pigs. 
We have pleasure in acknowledging the 
receipt of the third and fourth numbers 
of Natural Science, the new monthly review 
to which we called the attention of our 
readers in December last. Such an excellent 
work is deserving of every support. Among 
the contributors to the above numbers we 
note the names of Prof. G. Heuslow, Sir J. 
W. Dawson, Prof. Williamson, Mr. Lydek- 
ker, and other eminent naturalist. Messrs 
Macmillan & Co., London are the publishers 
A Fully Peopled Earth. — From a series 
of researches and calculations by M. Ra- 
venstein, a French geographer, it appears 
that over-population of the globe and the 
beginning of human decadence may be 
nearer at hand than most of us have sup- 
posed to be possible. The present popula- 
tion, 1,467,000,000 individuals, is distributed 
over the continents and islands, exclusive 
of polar regions, in the proportion of 31 
inhabitants to the English square mile. 
Dividing the entire land surface 46.250.000 
square miles, into three regions, tnis author 
finds that fertile lands occupy, in round 
numbers, 28,000,000 square miles, steppes 
14,000,000, and deserts 4,000.000. He esti- 
mates that the maximum number of persons 
■that can be supported throughout the 
respective regions is 207 per square mile on 
the fertile lands, 10 on the steppes, and 1 
per square mile on the deserts. The present 
average for India is 175, for China 205, for 
Japan 264. The investigator concludes that 
the greatest number of persons the entire 
land surface can sustain is 5,904,000,000. 
The total increase in population is now 8 
per cent per decade — being 8, 7 in Europe, 
6 in Asia, 10 in Africa, 30 in Australia and 
Oceanica, 20 in North America, and 15 in 
South America, — and at this rate the earth 
will have acquired all the inhabitants it 
can maintain in about 180 years, or in 2072. 
Quite curiously, this date is about that 
fixed by geologists for the exhaustion of 
Great Britain’s coal supply. 
Referring to the Tewfikieh College of 
Agriculture in a lecture on Egyptian agri- 
culture delivered at a meeting of the Society 
of Arts Prof. R. Wallace tells us that it was so 
named in honour of the late Khedive (Tewfik 
Pasha) who contributed much towards its 
success. It was started about two years 
ago by the Egyptian Government for the 
purpose of encouraging scientific, agriculture 
and it commenced with 60 students, who 
underwent a systematic course of instruc- 
tion in agri<u’tnre in the course of which 
a knowledge of improved rotations, of im- 
proved implements, and improved methods 
was acquired. The benefit of the institu- 
tions is already beginning to be felt in the 
country districts. 
Editor. J. H. Cooke. B.Sc., F.G.S., Malta. 
