supporting lamella

516 W. B.
ON CERTAIN POINTS IN THE STRUCTURE AND FUNCTIONS OF
THE ENDODERM OF MYRIOTHELA.
In any animal three main problems concerning the manipulation
of its food-stuffs present themselves. These are (1) the
disintegration and solution of its food; (2) the absorption of
the dissolved or liberated and unchanged material; and (3)
the distribution of the products of digestion. We might also
add to these the storage of prepared food-stuff. Many and
diverse reasons justify the statement that a cell is hampered
or, better, limited in the range of its activity by being loaded
with indifferent reserve nutriment; and it therefore becomes
almost the duty of a special tissue to store material, either as
a provision for some extraordinary metabolic effort, or as a
consequence of an infrequent and uncertain food-supply. In
the case of Myriothela we shall see that this last problem—
the storage of reserved nutriment—occupies a large part of
the endoderm.
The disintegration of the food in all animals not possessed
of a masticatory apparatus is a process of solution differing
only in degree from the final solution of the smaller particles.
Yet I think we are justified in speaking of the whole act as a
process of disintegration and solution, because of the very
general tendency of animals to divide the process into those
two stages, and to differentiate the alimentary tract into a
special region where disintegration of the food by solution
takes place, e. g. the stomach of Vertebrates, and another
tract where solution is completed, and where solution and
absorption go on hand in hand.
In an animal of any considerable size the distribution of the
products of digestion becomes a problem of the utmost importance,
not only physiologically, but also from its far-reaching
influence on the morphological characters of animals. It has
been solved in three main ways :
1. By the utilisation of the enteric space itself, which functions
in part as a digestive cavity, and in part as a common