Water in Relation to Health and Disease. 731 
polish and becomes dull and scurfy, the coat stares, and a general 
state of unthriftiness is induced. Stone in the bladder may, 
in some circumstances, result from the continued use of hard 
water. Goitre, a disease marked by swelling of the glands of 
the neck, is also said by Professor Kendall to arise out of this 
cause, but our experience of the malady in lambs and horses 
does not enable us to confirm this view of its origin. 
Physiology of Water. 
The purposes which water serves in the economy of nature 
are many and various, and its importance in the maintenance of 
life is emphasised by the fact that it forms the chief inorganic 
constituent of all organised bodies ; in fact animals and vege- 
tables alike, from the highest to the lowest, may be regarded as 
more or less complex groups of cells of which water is the main 
constituent. In the higher animals, not only is water con- 
tained within the cells of every tissue, but there is a ceaseless 
current passing over and between them, into them and out of 
them, from which they are nourished and renovated. The 
tissues of the body indeed are constantly being irrigated and 
saturated with liquid nourishment which oozes through the 
walls of the minute blood vessels as so much flesh food in solution. 
In the body of the higher animals water forms as much as 
75 per cent, of the whole, while in the lower and simpler forms 
of life it reaches as much as 90 per cent. It is of course vari- 
ously distributed through the different parts of the body, but it 
enters into all, from the soft juicy muscle to the hard ivory and 
enamel constituents of the teeth. The quantity contained 
in any particular organ will vary from time to time. It is no 
doubt most considerable during the period of greatest functional 
activity and diminishes in the periods of functional rest. It is 
more abundant in the organs of the young than in those of the 
aged; hence the more juicy nature of the tissues of the former 
as compared with the latter. The following table shows the 
quantity of water contained in 1,000 parts of different animal 
tissues and fluids : — 
Tissues. 
Kidneys 
. 827 
Brain . . 
750 
Fat . 
299 
Heart 
. 792 
Skin . 
720 
Bone . 
216 
Nerve 
. 780 
Bone marrow 
697 
Ivory. 
100 
Spleen . 
. 758 
Liver . 
693 
Enamel of tooth . 
2 
Muscle . 
. 757 
Cartilage . 
550 
Fluids. 
Sweat 
. 995 
Gastric juice 
973 
Bile . 
864 
Saliva . 
. 995 
Milk . 
891 
Blood 
791 
Tears . . 
. 982 
