No. 2.] THE ADHESIVE ORGAN OF AMIA. 481 
lumen a beaded appearance. The diameters of the narrower 
and wider portions are to each other as one to five or six. 
On the anterior face of the organ there are no grooves cor- 
responding to the constrictions of the lumen, but on the pos- 
terior face a few such grooves are found. Each of the dila- 
tations marks the fundament of a closed spherical vesicle, and 
each diverticulum is found to break up subsequently into as 
Fic. E.—Longitudinal section passing through one of the halves of the 
adhesive organ of an embryo of a stage a little later than that shown 
in Plate, Fig. 3. Lettering as in the preceding figures. The por-: 
tion of the adhesive organ seen in the figure shows three dilatations 
of its cavity. The central one is not cut through its middle, and is 
therefore not well marked. Camera outline, details from photograph. 
< about 170. 
many such vesicles as there are dilatations formed in its lumen 
at this stage. The head cavities are but little changed from 
the preceding stage. 
The fifth stage; a. The Adhesive Organ. Yrom the fourth 
stage to the fifth or hatching stage, the adhesive organ passes 
through a series of progressive changes which cannot well 
be described separately. There will be given first an account 
of the conditions at the time of hatching and then an analysis 
