418 
NATURE 
[AuGusT 31, 1899 
increasing the flow of bile without increasing the solid 
constituents ; and so forth. Research of this description 
has been and is being carried on in the health resorts 
of this country, and though finality has by no means been 
reached, yet such endeavours to add to our knowledge 
should go far to enhance the reputation of each, to in- 
crease the confidence of patients who seek health there, 
and to remove any lingering prejudices that may still 
remain in the minds of scientific men as to the true worth 
of such treatment. 
With regard to the baths, inquiry as to their mode of | 
action has proved quite as satisfactory as in the case of | 
the mineral waters. Through the forward policy adopted 
at Harrogate in providing a new and magnificent suite 
of baths including almost every variety, and replete with 
every modern convenience, it is possible there to under- 
take and carry out any line of balneo-therapeutic treat- 
ment that may be desired. The methods in use at the 
continental spas have been adopted and in some cases 
improved upon, any new development being at once in- 
stalled and its utility or otherwise determined. The 
baths available, using the word bath in its widest sense, 
The factors at work in the human organism that are 
disturbed in greater or less degree by even simple baths 
are so many, and their interaction so complex, that it 
becomes a matter of great difficulty, in the first place to 
measure them, and, in the second place, to estimate 
their relative importance ; while in the case of the more 
complicated baths, where different elements, thermal, 
chemical or mechanical, are brought into play to disturb 
these factors, some in one direction and some in another, 
often apparently in direct opposition to each other, the 
difficulty becomes even greater. Thus, while we are 
able to ascertain approximately the net physiological 
result in any given case, it is impossible in the present 
state of our knowledge to do more than hazard conjec- 
tures as to the exact mode by which that result was 
produced—to what extent one factor was concerned and 
to what extent another. Still, in spite of the difficulty, 
collation of the results of various workers at home and 
_ abroad enables us te understand in some degree the 
rationale of bath treatment, and to place it on a sound 
physiological basis. 
The influence of bathing in its various forms on the 
animal economy is profound, and no 
one who has not specially observed 
the effects produced can form an 
adequate idea of how potent that in- 
fluence is. Broadly speaking, it may 
be said that the effects produced are 
the result of changes that take place 
in the circulatory system, which is the 
system mainly acted upon by the 
factors—thermal, chemical or mechan- 
ical—that may be at work. 
The heart, driving the blood with 
its contained nutriment, derived from 
the alimentary canal, through a closed 
system of tubing, consisting of arteries, 
capillaries and veins, enables that fluid 
to penetrate to all parts of the body, 
there to deliver up its charge of food 
to the tissues by interchange of fluid 
through the thin capillary wall; re- 
ceiving in exchange the waste products 
from the tissues, and bearing them 
away to be eliminated from the system. 
Variations in the amount of blood, 
and the force with which it is driven 
into the circulation at each heart beat, 
and variations in the calibre of the 
closed system of tubing will, with 
Greaves.) 
Fic. 4.—The combined needle and douche bath. 
may be classified into (a2) Thermal baths, depending 
for their action mainly on the element of temperature, 
and including plain water baths, hot and cold, Turkish, 
Russian, superheated air baths, &c. (4) Thermo-chemical 
baths, in which there is added to the effects of temper- 
ature the effect of the chemical constituents of the water. 
‘They include the saline sulphur baths, alkaline-sulphur 
baths, saline baths, Nauheim baths, &c. (¢) Thermo- 
mechanical baths, in which there is added to the effect of 
temperature the mechanical action of the water in the 
form of sprays, douches, effervescence, &c., with or with- 
out the mechanical effect of massage. These include 
the needle bath, combined needle and douche, running 
sitz bath, &c., and those with massage, the Aix douche 
and the Vichy douche. (@) Zhermo-electrical baths, in 
which a current of electricity, either constant or inter- 
rupted, is passing through the water. 
Each and all of these baths have their special effects, 
and abundant observations have been made to determine 
them experimentally as a guide to their intelligent use. 
NO. VOL. 60] 
1557) 
other factors, determine the tension 
of the circulation, or fluid pressure 
under which the blood is working—the 
blood pressure, as it is called. These 
variations are controlled by a nerve apparatus, the 
vaso-motor mechanism, whereby dilatation of vessels in 
one region of the body is compensated for by contraction 
in another, and the average level of blood pressure main- 
tained, or changes produced therein. On the integrity 
of this nerve mechanism, and the perfect performance 
of its functions, the maintenance of health largely 
depends, for by it the ebb and flow of vessel constriction 
and dilatation is controlled, and the circulation enabled to 
adjust itself to the rapid succession of changes that take 
place in the environment of the organism—changes due 
to gravity, posture, exercise, digestion and the like. 
Further, on these changes in blood pressure depends to 
a large extent the ebb and flow of fluid through the 
capillary wall, whereby nourishment is conveyed to and 
waste products removed from the tissues; and, con- 
sequently, where this function is impaired the nutrition 
of the whole body suffers. By the recent introduction 
of new instruments it is possible to measure directly the 
blood pressure in the human subject, and to observe its 
Harrogate. 
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