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PHYSIOLOGICAL CONSIDERATION OF CELLS. b21
special excitations from the nervous system, etc. Increased stimula-
tion of this kind may, as a fact, lead not only to intensified functional
metabolism in the tissue concerned, but even to hypertrophy of its
elements. Such hypertrophies, which we may call functional hyper-
trophies or hypertrophies of action, are specially common and remark-
able in muscles and glands (heart-muscles, bladder-muscles, kidneys,
etc.). As we have said, they are referable, in part at least, to increased
vital activity in the cells, consequently upon increased physiological
stimulation. A second possible factor is increase in the supply of nutri-
ment. This plays a chief part in hyperplastic processes, at any rate.
A third is the removal of the normal checks to growth. Its effect is
most evident in the processes described as regenerative. If we attempt
in particular cases to make out to which of these factors cell-multipli-
cation is due, we are led to see that it is rare for any one factor alone to
be the efficient cause.
" The remarkable regulating mechanism of the vessels is so adjusted
that when the function of a tissue is increased, its blood-supply is
increased to correspond. In like manner, when the smallest fragment
of tissue is removed, the slight loosening of the surrounding texture is
enough to augment the stream of transudation from the vessels. In
consequence of these adjustments increased supply of nutriment plays
a great part in all the formative disturbances of nutrition.
" Cohnheim, in his Allyeiiieine Fdthologie, has insisted on the import-
ance of increased sup})ly of nutriment ev^en more strongly than we have
done. According to his view, it is the sole influential factor, compared
with which the intrinsic activity of the cell is quite secondary. We are
unwilling to condemn the cell to play so passive a part, but rather agree
with Virchow,^ who affirms that ' the cell is not nourished, but nour-
ishes itself.' Functional hypertrophy is therefore not to be looked
upon as the mere consequen(;e of the increased blood-supply to the
active organ.
" If the assimilative activity of the cells were not augmented, the
mere presence of a greater supply of nutriment would be valueless.^
'' We shall more readily comprehend the activity of the tissue-cells
i. e. their behavior under various conditions and the changes they pass
through, now at rest and now manifesting intense formative energy
if we consider first the vital manifestation of an organism that is uni-
cellular, micro-organisms of bacteria and yeast-])lants, and their mode
of life. If we reflect on the conditions essential for the multiplication
of such organisms, we note that the nature of the nutrient fluid is (next
after the adjustment of the temperature) the factor of liigher import-
ance. In suitably composed fluids the fungi develop much more luxu-
riantly than in those that are ill-suited. But we are not thereby justi-
fied in assuming that the cell plays a merely passive part—that all it
has to do is to take up the nutriment offered to it. The cell is, on the
contrary, active, and its activity has a special influence on the liquid
itself. It has the power to induce certain chemical changes in the
liquid, to decompose certain substances contained in it, and to change
' Cellular Palholngy.
^See Samuel's Al'lg. Path., 1879; Paget's Surgical Pathology, Lect. 3.
PHYSIOLOGICAL CONSIDERATION OF CELLS. b21
special excitations from the nervous system, etc. Increased stimula-
tion of this kind may, as a fact, lead not only to intensified functional
metabolism in the tissue concerned, but even to hypertrophy of its
elements. Such hypertrophies, which we may call functional hyper-
trophies or hypertrophies of action, are specially common and remark-
able in muscles and glands (heart-muscles, bladder-muscles, kidneys,
etc.). As we have said, they are referable, in part at least, to increased
vital activity in the cells, consequently upon increased physiological
stimulation. A second possible factor is increase in the supply of nutri-
ment. This plays a chief part in hyperplastic processes, at any rate.
A third is the removal of the normal checks to growth. Its effect is
most evident in the processes described as regenerative. If we attempt
in particular cases to make out to which of these factors cell-multipli-
cation is due, we are led to see that it is rare for any one factor alone to
be the efficient cause.
" The remarkable regulating mechanism of the vessels is so adjusted
that when the function of a tissue is increased, its blood-supply is
increased to correspond. In like manner, when the smallest fragment
of tissue is removed, the slight loosening of the surrounding texture is
enough to augment the stream of transudation from the vessels. In
consequence of these adjustments increased supply of nutriment plays
a great part in all the formative disturbances of nutrition.
" Cohnheim, in his Allyeiiieine Fdthologie, has insisted on the import-
ance of increased sup})ly of nutriment ev^en more strongly than we have
done. According to his view, it is the sole influential factor, compared
with which the intrinsic activity of the cell is quite secondary. We are
unwilling to condemn the cell to play so passive a part, but rather agree
with Virchow,^ who affirms that ' the cell is not nourished, but nour-
ishes itself.' Functional hypertrophy is therefore not to be looked
upon as the mere consequen(;e of the increased blood-supply to the
active organ.
" If the assimilative activity of the cells were not augmented, the
mere presence of a greater supply of nutriment would be valueless.^
'' We shall more readily comprehend the activity of the tissue-cells
i. e. their behavior under various conditions and the changes they pass
through, now at rest and now manifesting intense formative energy
if we consider first the vital manifestation of an organism that is uni-
cellular, micro-organisms of bacteria and yeast-])lants, and their mode
of life. If we reflect on the conditions essential for the multiplication
of such organisms, we note that the nature of the nutrient fluid is (next
after the adjustment of the temperature) the factor of liigher import-
ance. In suitably composed fluids the fungi develop much more luxu-
riantly than in those that are ill-suited. But we are not thereby justi-
fied in assuming that the cell plays a merely passive part—that all it
has to do is to take up the nutriment offered to it. The cell is, on the
contrary, active, and its activity has a special influence on the liquid
itself. It has the power to induce certain chemical changes in the
liquid, to decompose certain substances contained in it, and to change
' Cellular Palholngy.
^See Samuel's Al'lg. Path., 1879; Paget's Surgical Pathology, Lect. 3.
