stage, rigors, heat of skin, accelerated pulse, furred tongue,
loss of appetite, thirst, epigastric uneasiness, vomiting, headache,
pains in the back and limbs, muscular weakness, convulsions, delirium,
&c.; in the second stage, cutaneous eruption, itching, tingling, sore
throat, swelled fauces, salivation, cough, hoarseness, dyspnoea, &c.;
and in the third stage, oedematous inflammations, pneumonia, pleurisy,
diarrhoea, inflammation of the brain, ophthalmia, erysipelas, &c.:
each of which enumerated symptoms is itself more or less complex.
Medicines, special foods, better air, might in like manner be instanced
as producing multipled results. Now it needs only to consider that the
many changes thus wrought by one force upon an adult organism, will be
in part paralleled in an embryo organism, to understand how here also,
the evolution of the homogeneous into the heterogeneous may be due to
the production of many effects by one cause. The external heat, which,
falling on a matter having special proclivities, determines the first
complications of the germ, may, by acting on these, superinduce further
complications; upon these still higher and more numerous ones; and so on
continually: each organ as it is developed serving, by its actions and
reactions on the rest, to initiate new complexities. The first
pulsations of the foetal heart must simultaneously aid the unfolding
of every part. The growth of each tissue, by taking from the blood
special proportions of elements, must modify the constitution of the
blood; and so must modify the nutrition of all the other tissues. The
heart's action, implying as it does a certain waste, necessitates an
addition to the blood of effete matters, which must influence the rest
of the system, and perhaps, as some think, cause the formation of
excretory organs. The nervous connexions established among the viscera
must further multiply their mutual influences; and so continually. Still
stronger becomes the probability of this view when we call to mind the
fact, that the same germ may be evolved into different forms according
to circumstances. Thus, during its earlier stages, every embryo is
sexless--becomes either male or female as the balance of forces acting
on it determines. Again, it is a well-established fact that the larva of
a working-bee will develop into a queen-bee, if before it is too late,
its food be changed to that on which the larvae of queen-bees are fed.
All which instances sug