is much more frequent in some
tissues than in others. According to recent statistics prepared by the
registrar-general for England and Wales (sixty-seventh annual report)
the most frequent seats are, in numerical order, as
follows:--_males_--stomach, liver, rectum, intestines, aesophagus,
tongue; _females_--uterus, breast, stomach, liver, intestines, rectum.
Other statistics give similar, though not identical results. It may be
said, broadly, that the most frequent seats are the female sexual organs
and after them the digestive tract in both sexes. In children, in whom
cancer is rare, the most frequent seats appear to be--under five, the
kidneys and supra-renal bodies; five to ten, the brain; ten to twenty,
the arm and leg bones.

Cancer tends to advance steadily to a fatal termination, but its
duration varies in different cases according to the part affected and
according to the variety of the disease. Soft cancer affecting important
organs of the body often proves fatal in a few months, while, on the
other hand, cases of hard or epithelial cancer may sometimes last for
several years; but no precise limit can be assigned for any form of the
disease. In some rare instances growths exhibiting all the signs of
cancer may exist for a great length of time without making any progress,
and may even dwindle and disappear altogether. This is called
"spontaneous cure."

Cancer research.

Cancer has been the subject of observation from time immemorial, and of
the most elaborate investigation by innumerable workers in recent years;
but the problems of its origin and character have hitherto baffled
inquiry. Modern scientific study of them may be said to have begun with
J. Muller's microscopic work in the structure of cancerous tissue early
in the 19th century. A great impetus to this line of investigation was
given by the cellular theory of R. Virchow and the pathological
researches of Sir J. Paget, and general attention was directed to the
microscopic examination of the cells of which cancer is composed. This
led to a classification, on which much reliance was once placed, of
different kinds of cancer, based on the character of the cells, and
particularly to a distinction between _carcinoma_, in which the cells
are of the epithelial type, and _sarcoma_, in which they are of the
connective tissue type. The distinction, though still maintained, has
proved barren; it never had any real significance, either clinical or
pathol