Mr. Howard Martin on Oysters. 197 
The principal enemies of the oyster are crabs, five-fingered 
starfish, dog-whelk or whelk-tingle, according to Frank Buckland 
a kind of sponge called Cliona, the spat of mussels (this is 
doubtful), and the blanket-weed; the last two destroy the oysters 
by smothering them. Sand-storms, a rush of water chilled by 
melted snow, or a sudden fall of snow, will also destroy the 
oysters. Thefts of oysters are very common, and watch-boats 
are necessary in most fisheries. 
The food of oysters consists of very minute animal or vegetable 
organisms. The flavour and quality of oysters are very much 
affected by food, e.g. some oysters at Falmouth are poisonous 
owing to the copper in the water. If typhoid fever has been 
caused by oysters, it was possibly due to the dirty water in the 
tubs (possibly containing typhoid germs), into which the oysters 
are put after being brought to market. It is extremely im- 
probable that typhoid germs impregnate oysters in the fisheries. 
Dirt and sewage are extremely bad for oysters, and typhoid 
germs do not flourish in clean sea-water. The results of experi- 
ments made by Professors Hermann and Boyce showed that 
oysters fed with sugar, or with flour or oatmeal, died; fed with 
living protozoa or protophyta, lived and throve; that the effects 
of stagnation of water were very deleterious ; but that oysters 
could tolerate a considerable quantity of sewage, and live for a 
- long time in water opaque with fecal matter, though typhoid 
fecal matter proved more quickly fatal than that from healthy 
subjects. No increase of the typhoid bacilli could be discovered 
in the oysters thus exposed to the infection; on the contrary, 
the bacilli appeared to decrease in the passage along the ali- 
mentary canal, and they would not flourish in clean sea-water. 
The presence of sewage in any quantity in fisheries has often 
been found to be fatal to oysters, e.g. more than one million and 
a half of oysters were destroyed by sewage in the river Median in 
1871. Soil and water have a great influence over the growth 
and quality of the oyster. 
For breeding the parents should be laid in quiet waters with 
an equable temperature. For fattening or growing oysters, 
shallow water with a strong current and a certain admixture 
of fresh water is best. The best soil for growing or fattening is 
London clay ; sand or gravel is bad. 
Mr. Buckland calculated the cost of the meat of the oyster per 
pound as 9s. 4d. for natives and 8s. for ‘“‘seconds’’; they would 
not therefore pay to eat as nourishment apart from inclination. 
There are two branches of oyster culture, viz. protecting the 
growing oysters from injury or theft in open waters, and collect- 
ing and protecting the spat in enclosed ponds. And oyster 
fisheries may be divided into four classes, viz.: (1) natural beds, 
usually more or less in the open sea; (2) beds which are partly 
