458 JOURNAL OF SCIENCE. 
part of the fry shell which comes into direct contact with the ob- 
ject to which attachment occurs ; and that the hinge-end of the 
larval or fry shell is directed somewhat upwards, the line of junc- 
tion of the valves having at first formed an angle of nearly thirty 
degrees with the plane of the surface to which fixation occurred. 
This condition of things isso invariable that it may be regarded 
as universally the case. How does the fixation occur? A bys- 
sus at most would only serve for temporary anchorage ; and we 
find that as soon as the first calcareous deposits are formed to 
build the asymmetrical valves of the spat, the lower valve of the 
latter is for the first time glued down by the conchioline or perios- 
tracum covering it externally, and that it often continues to be 
so affixed until it is nearly two inches in diameter. After this 
the lower valve of the spat becomes free, and the free margin of 
the shell begins to be bent upwards. The valves of the sym- 
metrical fry are also laminar and homogeneous in microscopic 
structure ; while the very first layers of calcic. carbonate deposited 
to form the spat shell are prismatic and of a wholly different 
microscopic appearance from that ofthe fry. The facts presented 
above prove beyond a doubt, that it is the mantle border of the 
fry which is the effective agent in the achieving firm fixation, 
whatever may be the importance of a temporary or larval 
byssus. | 
This was an interesting and important point to determine, on 
account of its practical relation to the artificial rearing of the 
American oyster (Ostrea virginica). But with the foregoing 
comparatively meagre results we may say that our success in the 
artificial culture has ended; and were it not for the highly 
encouraging recent reports from France, our efforts might have 
rested here. The stimulus which has provoked the investigations 
recently undertaken abroad was, however, probably Dr. W. K. 
Brooks’s success with the American oyster in 1879, and his 
demonstration of its unisexuality. 
The remarkable success of M. Bouchon-Brandelly in rearing 
spat from the artificially fertilised ova of O. angulata at Verdon 
in France, as reported in the Auzals and Magazine of Natural 
FHitstory for October, 1882, and his still later reports to the minister 
of marine of France in the Journal officiel de la republique fran- 
caise, are of the greatest moment as applied to practical oyster- 
culture. M. Brandelly, after determining that O. angulata was 
unisexual like the American species, conceived the idea of 
rearing the spawn by artificial means. In order to do this, two 
adjoining oyster claires, or ponds, fed by the tide, were arranged 
at Verdon ; the one acting as a resorvoir from which the fresh 
sea-water (brackish) was drawn through a tube, provided with a_ 
filter consisting of a sponge at either end, into the lower experi- 
mental claire. The water percolated out of the latter through a 
bed of fine sand ; in this way the embryonized ova placed in this 
pond were kept fiom escaping. Fertilised eggs were then put 
into the experimental pond from day to day, while a number of 
collectors or tiles were at once submerged in the same. In some- 
ee eT — —— ee a Pr. 
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