All the figures reproduced (Plates 1 to 13) represent photographs
taken with the Bausch and Lomb Photomicrographie Camera Gl. It
would have been preferable to use colored figures in order to simplify
description and to bring out more clearly the difference in appearance
of the constituent parts of the muscular elements and the interstitial
connective tissue. It is often diflBcult to appreciate in a photograph
what belongs to the Purkinje cell and what should be considered as
endomysium or perimysium. These features, however, are perfectly
clear in the preparations. We shall attempt to remedy this defect, at
least in part, by indicating precisely the elements most important from
the point of view of our description. Photography on the other hand
offers a very great advantage, in that it reproduces faithfully and
much better than any drawing the morphological appearance of the
different varieties of Purkinje fibers, some more or less embryonic in
type, some more advanced in their evolution representing stages of
transition towards cardiac fibers, and also of myocardial fibers properly
so called.
We do not intend to describe the topography of the atrio-ventricular
bundle, but shall content ourselves with making a histological study
of Purkinje fibers in the normal heart, emphasizing the different stages
in their evolution and the characters in which they differ from cardiac
fibers at various levels of the atrio-ventricular bundle. By this study
we shall be able to determine that in the pathological heart the Purkinje
cells undergo an identical evolution carried, however, to pathological
excess even to the point of atrophy and complete disappearance.
