776 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [24] 
sky, which is really the true cause of the phenomenon. In like man 
ner with the oyster banks; just in proportion as they diminished in size, 
as became manifested by vacant places appearing where oysters formerly 
grew, people said of the work of destruction, here it is mud or sand; 
there mussels; and at other places the maérle, without reflecting that the 
dredge which, in tearing up the soil and plowing over the beds, 
brutally and ruthlessly destroying countless oysters, young and old, 
was the prime cause of these vacancies and of the filling in by mud 
and sand which shortly followed. This can be easily understood. When 
a bed of oysters is intact, that is, before the dredge has commenced 
its work of destruction, the oysters, congregated upon the rocks and 
pebbles, firmly united to one another and superimposed without order, 
form at the bottom of the sea a complicated network of prominences 
and hollows, of tortuous channels and rocky crests. When, during 
high tide, these beds are covered with several meters of water, which 
always holds quantities of mud in suspension, the tendency is always 
for this mud to be deposited upon the beds, and it is actually deposited 
during tidal changes. But when at low tide the water passes down 
the beds, the eminences and crevices of the bottom formed by the 
irregular disposition of the oysters constitute so many obstacles to its 
onward flow, that it is divided into a thousand little streamlets, which, 
however calm the sea may be, form a sufficiently rapid current to carry 
away any mud which may have been deposited, and in this manner sub- 
ject the oysters to a sort of hygienic cleansing. So true is this, that the 
fishermen to whom the government conceded the tidal or emergent lands 
of the island of Ré, which formed an immense sand-flat or sand-morass, 
working from these data, undertook and succeeded in obtaining, in a 
relatively very short time, the entire removal of the deep mud which 
rendered their lands sterile. They paved the muddy bottom of their 
territory with irregular fragments of rock taken from the island, and by. 
ingeniously varying the hollows and eminences, so as to break up the 
water into thousands of currents and streamlets, they had the satisfaction 
of seeing the mud sensibly diminished in depth with every tide, and the 
young growth of oysters coming in from the open sea soon took possession 
of this territory, which had been so long deserted by these animals. By 
the accumulation of the oysters upon the rocks which follows this reclama- 
tion, the beds are preserved from mud and sand, and consequently from 
the invasion of mussels; but as soon as the dredge is used indiserimi- 
nately upon this surface, and a vacant place or hollow produced, where 
the water can remain stagnant at each flood tide, a deposit of mud soon 
forms, which augments every day, gaining perceptibly in length and. 
breadth, invading the oysters, leveling the bottom, and tending by 
its presence even to destroy the beds and at the same time to favor the 
birth and development of mussels. It is the same with the maérle, 
which is the common name for a submarine plant, an alga, having a 
kidney-shaped form, and closely resembling both in shape and appear- 
