W. K. Brooks—Embryology of the American Oyster. 425 
. to me, however, that the evidence of this coincidence is not 
complete. 
In attempting to reason from these photographs as the matter 
now stands, it is necessary to try at every step farther experi- 
ments in order to find out whether the facts agree with hypoth- 
esis, and it is this very condition of affairs that gives hopes of 
results valuable in their bearing on terrestrial chemistry and 
physics. In the photographs of the spectrum of Vega there are 
eleven lines, only two of which are certainly accounted for, 
two more may be calcium, the remaining seven, though bear- 
ing a most suspicious resemblance to the hydrogen lines in 
their general characters, are as yet not identified. It would be 
worth while to subject hydrogen to a more intense incandes- 
cence than any yet attained, to see whether in photographs of 
its spectrum under those circumstances any trace of these lines, 
which extend to wave length 8700, could be found. : 
It is to be hoped that before long we may be able to investi- 
gate photographically the spectra of the gaseous nebule, for in 
them the most elementary condition of matter and the simplest 
Spectra are doubtless found. 
Art. L1.—Abstract of Observations upon the Artificial Fertiliz- 
ation of Oyster Eggs, and on the Embryology of the Amerian 
Oyster ; by W. K. Brooks, Associate in Biology, Jobns Hop- 
kins University. (Notes from the Biological Laboratory of 
the Johns Hopkins University). 
ALL the writers upon the development of the oyster, from 
Home (Phil. Trans., 1827), to Mébius (Austern und Austern- 
wirtschaft, 1877), state that the eggs are fertilized inside the 
ing season, and be pi: 
Same time to try to raise young for myself by the artificial fer- 
tilization of cans taken be the ovaries. I had complete.suc- 
