e
distinctly was it shown that by far the greater number of new formations
arise from the connective tissue. In almost all cases new formations may
be seen to be formed by a process of ordinary cell division from
previously existing cells. In some cases the cells continue to resemble
the parent cells; in other cases they become different. All new
formations built of cells which continue true to the parent type we may
call homologous new formations; while those which depart from the parent
type or undergo degenerative changes we may designate heterologous. In a
narrower sense of the word heterologous new formations are alone
destructive. The homologous ones may accidentally become very injurious,
but still they do not possess what can properly be called a destructive
or malignant character. On the other hand, every kind of heterologous
formation whenever it has not its seat in entirely superficial parts,
has a certain degree of malignity, and even superficial affections,
though entirely confined to the most external layers of epidermis, may
gradually exercise a very detrimental effect. Indeed, suppuration is of
this nature, for suppuration is simply a process of proliferation by
means of which cells are produced which do not acquire that degree of
consolidation or permanent connection with each other which is necessary
for the existence of the body. Pus is not the solvent of cells: but is
itself dissolved tissues. A part becomes soft and liquefies, while
suppurating, but it is not the pus which causes this softening; on the
contrary, it is the pus which is produced as the result of the
proliferation of tissues.

A suppurative change of this nature takes place in all heterologous new
formations. The form of ulceration which is presented by cancer in its
latest stages bears so great a resemblance to suppurative ulceration
that the two things have long since been compared. The difference
between suppuration and suppuration lies in the differing duration of
the life of different cells. A cancer cell is capable of existing longer
than a pus corpuscle, and a cancerous tumour may last for months yet
still contain the whole of its elements intact. We are as yet able in
the case of very few elements to state with absolute certainty the
average length of their life. But among all pathological new formations
with fluid intercellular substance there is not a single one which is
able to preserve its existence for any length of time--