4944 THE ZooLocist—J UNE, 1876. 
by our own countrymen. Fond as | am ofa good native, 1 would 
not advise such a breach of “ free trade” policy as this; but, in my 
opinion, it is is the only real plan to secure a cheap oyster. 
Much may be done also by regulating—not stopping —the 
summer working of oyster-beds. Dredges should be so constructed 
as to leave the year-old oysters, and bring up only two-year-olds, 
weeds, five-fingers and dog-whelks. 
C. R. BREE, 
S1r,—In the ‘ Field’ of April 15th there appeared a communica- 
tion from Mr. W. Saville-Kent on the subject of “ The Propagation 
‘of the Oyster,” in which the evidence given by Mr. Austin before 
the Select Committee of the House of Commons, and also certain 
facts observed with regard to the spatting of Modiola modiolus, are 
quoted in opposition to the opinion entertained by most scientific 
naturalists that the oyster is hermaphrodite. 
Mr. Saville-Kent considers that “there are strong grounds for 
believing that Mr. Austin’s deductions concerning the sexual indi- 
viduality of the oyster are correct,’ and that the black spawn 
consists of ova produced by a female oyster, while the “ white sick” 
is the milt of the male, and that the former can only be fertilised by 
being brought into contact with the latter. 
This theory is combated in a letter from Dr. Bree in the suc- 
ceeding number of the ‘ Field,’ in which the history of the develop- 
ment of the ova into the perfect oyster is fully described; but some 
further evidence of the fallacy of the unisexual theory is desiderated. 
I have waited another week, and still none of your correspondents 
furnish the results of their observations on this point. I therefore 
venture to ask to be allowed to make the following contribution 
to the stock of information which microscopic investigation has 
elicited with regard to the early history of the oyster, and I think 
my observations prove that, certainly, “ white sick” is not milt, but 
that it consists of ova, which, without commixture with other 
spawn, can be developed into embryo oysters such as those found 
by Mr. Austin in his examination of the “ black sickness.” 
On the 27th of May, 1865, one of my dredger friends, hearing 
that I wanted a “sick” oyster, brought me one, which, on an attempt 
being made to open it, had proved to be “milchy.” On being 
placed in a vessel filled with sea-water it began to emit the spawn, 
