No. 2.] THE HYPOPHYSIS OF AMIA. 507 
6 of the preceding article, and (by using very great care) in 
somewhat earlier stages. 
A comparison of our Fig. 4 with Prather’s Fig. 3 of approx- 
imately the same stage will show the differences between eggs 
preserved with and without removal of the membranes. 
From the foregoing we believe that Prather is in error in 
regarding the hypophysis as of entoblastic origin. Prather 
gives a brief summary of opinions that have been hitherto 
held as to the origin of the hypophysis. From this it appears 
that the view that the hypophysis is of entoblastic origin 
exclusively has not been maintained since 1882. Nearly all 
recent writers have maintained its ectoblastic origin (though 
a few have regarded it as of mixed origin). We believe that 
we have shown that Amia, also, must now be placed among 
those forms concerning the ectoblastic origin of whose hy- 
pophysis there is no question. 
Prather believes that the structure which v. Kupffer (1893) 
has described and figured in early stages of Acipenser (Figs. 
13, 14) as the hypophysis is in reality the adhesive organ of 
that form. This belief he bases on the two facts; that the 
hypophysis is described by v. Kupffer as laden with food yolk, 
and that it has the appearance of being a dorsal diverticulum 
of the entoblast. Both of these characteristics distinguish 
the adhesive organ of Amia, and may be expected to be 
characteristic of that of Acipenser also. An investigation in 
progress in this laboratory on the adhesive organ of Lepi- 
dosteus has given figures of median sections strikingly like 
Fig. 13 of v. Kupffer (1893). In these sections there is in 
front of the brain an entoblastic tube with its lumen’ and 
walls continuous below with those of the foregut. The tube 
is flattened and may be traced in series of longitudinal sec- 
tions from one side of the brain to the other. It is therefore 
as wide as the brain. Its position and relation to surrounding 
structures are the same as that figured for the hypophysis of 
Acipenser by v. Kupffer, but its subsequent history shows it 
to be the adhesive organ. These observations on Lepidos- 
teus certainly lend weight to Prather’s suspicion. On the 
