202 THE AMERICAN MONTHLY [November, 
but the learner, to reach these cells, must employ a higher magnifying power 
—one of 240 diameters is sufficient. 
With this power the appearance is such as is shown in figure 2. ‘Eenesthe 
beginner should follow much the same course of pisesdion as was detailed 
in the earlier pages of this article, where he proceeded from his numerous ac- 
tual observations by appearances in his sections to interpret or put together the 
real actual structures which he does not see at any one time or place in their 
entirety. We shall not occupy the reader with such a tedious course again, 
having already insisted upon the necessity of pursuing just such a tedious 
course, until the eye and judgment are trained, but will in this chapter 
assume that he has profited by all the lessons of the first chapter, and can 
look beyond the appearance he has in his section. He finds at once a very 
different tissue from the one so widely found in the green gland. Through- 
out the tubules, excepting at their tips and at their opening into the main 
duct, he finds, first, an arrangement of matters which seems to be radial from 
the centre of the section but stopping short to leave the empty star-shaped 
lumen in the centre. Half way across the rays he finds dense oval bodies 
with a still denser central body inside them. The radial matter is not 
entirely continuous, perhaps, but breaks here and there seem to leave empty 
spaces, though the lumen is bounded by a line iv which no breaks are seen. 
The tubule also is surrounded by a hard line in which there are no breaks. 
These briefly are the various facts he at first observes. Closer observation of 
the radial matter shows to him here and there a sharp line in places; he can 
perhaps trace it down from the lumen, and it may seem to surround some 
of the finer matter and one of the dense oval bodies. By a few examina- 
tions he can convince himself that the epithelium is made up of a row of 
cylindrical bodies which are not nearly as straight-sided as the cubical 
blocks which line the cavities of the green gland or nearly so regular in 
outline. Some are globular and tapering, others are long and narrow and 
somewhat wavy; they are very seldom perfect cylinders, yet they fit together 
so as to fill in the wall, and the long axis of the cell runs at a right angle 
with the long axis of the tube and radially from a common centre. These 
bodies are the cells, the units, which taken together form the glandular tissue 
of the liver. The shapes of individual cells can be seen here and there at 
favorable places, and such a place is represented in figure 3. 
But what of the breaks in the epithelium so very conspicuous in the figures 
2and 3° Here thé observer has before him an appearance which every 
consideration goes to show is abnormal and is the result of some imperfec- 
tion in the treatment. The simplest proof that it is abnormal is given by 
the fact; easily proved, that it occurs only here and there and at no definite 
intervals, and that it does not occur in sections treated in a different way. 
The nature of the imperfection may be seen—a very slight shrinking through- 
out the epithelium, so that the cells in places no longer form a continuous 
wall for the tubule in all places. That the imperfection has not been so 
serious as to utterly ruin the sections is shown by the fact that the walls of 
many of the cells are unbroken and the outline of the central body, the 
nucleus, is entire, and the lining next the tubule is entire. We see then that 
we can learn much from the Sechiont though we cannot, of course, be as con- 
fident in doubtful matters as we could be fn the section were per fect. 
It having been settled that the shape of the cell is some modification of a 
cylindrical form, we may inquire further of its parts, and find that it is made 
up of granular matter which stains very readily with most of the reagents— 
it is the protoplasmic content of the cell. In the centre of the cell, some- 
times nearer the end toward the lumen, usually more deeply situated, is the 
oval body, the nucleus, with its very sharp limiting line and within granular 
