No. 405.] THE INTESTINE OF AMIA CALVA. 723 
of the valve. Comparatively few run in the other direction. 
The muscularis mucosa at the base of the spiral valve is not 
especially thickened or diminished; it occupies its usual posi- 
tion on the ental side of the stratum compactum. The con- 
nective-tissue layer of the stvatum compactum on each side of a 
turn of the spiral is seen in section to send upward into the 
spiral valve a thick portion of connective tissue ; on the ental 
surface of each of these portions is the usual muscularis mucosa. 
These two layers meet in the basal part of the valve to form a 
sort of arch. Beneath the arch thus formed are muscle fibres 
composing one large bundle or several small bundles. It may 
be seen that in this way muscle and connective tissue are con- 
siderably mixed up in the basal part of the valve ; but farther 
entad all become arranged once more, the muscle occupying 
the center of the valve, while on each side of it, between it and 
the submucosa, is a rather dense band of connective tissue ; 
these bands, however, are not so dense as to prevent muscle 
fibres from going up into the villi (Fig. 9). 
Three conclusions are to be drawn from the above compli- 
cated condition. First, the relative position of muscle and 
connective tissue is somewhat different from that in the in- 
testine in general. Secondly, the core and, in fact, a large 
part of the spiral valve are made up of muscular tissue. 
Thirdly, there is more muscle in the spiral valve than the 
double thickness of the muscularis mucosa, and although a 
small part of the muscle is derived from the muscularis mucosa, 
by far the larger part is not. 
The intestinal epithelium of Amia presents a very interest- 
ing condition. The cells are exceedingly small, and in most 
places it is impossible to make out in sections the cell outlines. 
Macallum (86) describes the epithelium to be composed of 
short cylinder cells resting on four layers of nuclei. This is 
often the appearance presented in sections; sometimes there 
seem to be six or eight layers of nuclei, especially in the upper 
part of the intestine ; possibly, at times, a few of these nuclei 
"y be those of underlying cells. Macallum figures the nuclei 
in even layers; this is seldom the case, the nuclei seeming to 
be scattered irregularly through the epithelium. They are 
