142 _ SEVENTH REPORT—1837. 
the process by which the new bony matter necessary for union 
is produced, is often morbidly carried on in the matters which 
inflammation has deposited in the surrounding structures. The 
most striking illustrations are undoubtedly those which are pre- 
sented by the heterologue structures, probably because of their 
being much more readily produced accidentally than the ana- 
logue. Thus we see that the natural structures in the neigh- 
bourhood of malignant tumours are apt to degenerate into a 
substance in some respects resembling that of the original tu- 
mour. In the neighbourhood of those tumours which are of 
slow growth, and of cartilaginous hardness, we often find the 
surrounding structures, but more especially the cellular memn- 
brane, partaking of the same character of hardness, though ne- 
cessarily wanting the structural arrangement which characterizes 
the tumour itself. In the same way we find that those tumours 
which are composed of a soft and brain-like substance are sur- 
rounded by natural structures, which degeneration has converted 
into a nearly similar substance, or which have a similar matter 
deposited intersticially. Again, in those tumours which are 
remarkable for their black colour, and to which the name of 
melanosis has from this cireumstance been applied, the sur- 
rounding structures become more or less deeply tinged with a 
black or dark-coloured material. This disease also presents us 
with a good illustration of the principle in a mode precisely the 
converse of the preceding example. There is, perhaps, no organ 
so liable to be affected with melanosis as the eye; and it may 
not unreasonably be suspected that it is the natural and healthy 
production of black pigment, performed by the choroid coat of 
this organ, which is the chief cause of this predisposition. 
The anatomical structure of a secreting organ is one of the 
conditions in which it is essential to consider in an inquiry into 
the phenomena of secretion, although it cannot be imagined that 
it affects it by any merely mechanical separation. If it were 
possible, it would be desirable to ascertain, and to indicate by 
definite terms, the comparative degrees of vascularity, the pro- 
portion in which the ramifications of the three vascular systems 
are combined, and the rapidity of circulation. The comparative 
innervation of the part, although probably no less important, is 
perhaps still less exactly ascertained. To improve our knowledge 
on this point, it would be particularly desirable to ascertain not 
merely the number of nerves sent in proportion to the size of the 
organ, but also their origin, and the proportion in which they are 
derived from the ganglionic and cerebro-spinal systems ; the de- 
gree of sensibility which they impart to the organ, the degree 
of uniformity or variation of function which may be observed in — 
