94 
BastiaNj on the so-called Pacchionian Bodies, 
inserted themselves into depressions in the cranial bones. 
In bodies picked out from, this last situation (where, perhaps, 
they are more protected from friction, as well as supplied 
with more nutriment from the cranial diploe) I have found a 
large quantity of epithelium, evidently in multiple layers, 
accumulated on their surface. A tendency to this is some- 
times seen also on the arachnoid itself, since cells may be 
recognised in diflPerent places lying over one another as though 
a double or even treble layer existed. In addition to this 
epithelial covering, the Pacchionian bodies are composed of 
fibrous tissue, which may be seen in all stages of develop- 
ment, either in the same or different growths. Everything 
I have observed during the examination of this tissue in these 
bodies tends to confirm the opinions of Henle and Virchow"^ 
— who are so far agreed as to the fact that the undulating 
fibres composing the bulk of its substance are derived from 
the direct fibrillation of a homogeneous, hyaline, and 
gelatinous-looking material — and lends no support to those of 
Schwann or even Reichert. In great part this homogeneous 
material seems to grow in the Pacchionian bodies in the form 
of a branched network, reticulating in all directions so as to 
produce a pretty compact sponge-like structure. A portion 
of these interlacing, structureless bundles, which was scraped 
from the surface of one of these bodies, together with 
epithelium, t is represented in fig. 5. In many parts of the 
interior of the growths an areolated arrangement of bundles 
may also be seen, apparently at a later stage of development, 
since their texture seems firmer, their outline more sharply 
defined, and in many of them, by a proper adjustment of 
light, faint linear markings can be recognised, which may be 
the first traces of fibrillation (fig. 6). A thin, transverse 
section of one of the more opaque bodies on the surface of 
the arachnoid reveals the full maturity of the tissue (fig. 7), 
and instead of a network of a homogeneous or faintly 
fibrillated aspect, we get one composed of ordinary areolar or 
fibrous tissue, the bundles of which present the same re- 
ticulated arrangemsaut. Occasionally I have seen a spiral 
fibre of elastic tissue of the kind mentioned by Luschka 
twisted around a still homogeneous bundle (fig. 5fl), and in 
portions of the surface fibrous tissue of these bodies which 
* 'Cell. Pathology.' Translation by Chance_(1859), pp. 41—45. 
t Tiie minute buds so frequently found projecting from the surface of a 
still growing Pacchionian body, and which are the origin of the various 
secondary and tertiary outgrow ihs, are small projections of a tissue of this 
kind, which gradually undergo differentiation and development as they 
increase in size. 
