J. LeConte—Glycogenic Function of the Liver. 25 
Tf the first step in the history of the laccoliths was the mak- 
ing of intersecting fissures narrowing upward, some reaching to 
the surface, it may be, and others to different levels in the 
strata, the trachytic lava passing up would tend to become 
thickened by cooling, or might even become solidified, in the 
upper part of such fissures, because of the large extent of the 
cooling surfaces as compared with the amount of liquid. But 
aloug their intersections it would be most sure to remain 
liquid, and here conduits would become localized, from which 
the upward forced liquid rock might spread laterally, what- 
ever the height, and produce the laccolith. The ready cool- 
ing of the trachyte would tend to limit the lateral flow of 
the lavas in such chambers, and so aid in producing the thick 
form of the laccolith, besides preventing a waste of energy. 
With intermissions in the flow, the trachyte of the chamber 
would be intermittent in its enlargement, and receive that 
degree of bedded structure which, according to Mr. Gilbert, 
exists. 
The facts give some hints as to the source of the great 
force producing the upflow of lavas in non-voleanic fissure- 
ejections. They make the vast extent of such outflows, as 
those over California, Oregon, India and other regions, intelli- 
gible. Volcanoes are small outlets compared with fissures that 
extend for miles, and the forces they command are feeble com- 
pared with the action which makes such fissures. The opening 
of one or more great fissures is the initial step in the making of 
a volcano; and the voleano is the open chimney or vent left 
after the fissure-action had spent its foree—a point illustrated 
by the writer in his account of the Hawaiian islands and their 
J. D. Dana. 
volcanic origin.* . 
Art. 1V.—Some Thoughts on the Glycogenic Function of the 
Liver. Il. Disposal of Waste; by JoserpH LeConre. 
[Read to the National Academy of Sciences, October 30, 1879.] 
IN my previous paper,t I attempted to show that the well 
known and remarkable fact that nearly the whole food absorbed 
from the alimentary canal is distributed through the liver be- 
fore it reaches the general circulation, is proof that, in a ver: 
Important way, the liver prepares the food for the uses to whic 
it is applied in the animal body: and further that the prepara- 
tion is accomplished by the glycogenic function. According 
to my view there are three sources of glycogen, viz: 1. The 
whole of the amyloids: these are arrested in the liver as glyco- 
* Expl. Exp. Rep. Geology, 1849. ¢ This Journal, xv, 99. 
