124 HEALTH AND DISEASE 



bone and the formation of calculous concretions. It may be remarked, 

 however, that the hardness of water is chiefly due to carbonate of lime, 

 and would not, therefore, be likely to be very largely concerned in the 

 formation of bony tumours, in which the phosphate of lime is the chief 

 constituent; but there is no doubt that lime salts would be likely to 

 contribute to the formation of calculous deposits in the digestive system 

 or in other parts of the body. 



It has already been stated that water forms a very large proportion 

 of the tissues of the animal body from 70 to 80 per cent, and in the 

 lower forms of living beings it may reach as much as 90 per cent. Pro- 

 fessor Axe, in his articles in the Royal Agricultural Society's Journal, 

 has given the following table, showing the amount of water contained 

 in 1000 parts of the various organs and structures: 



Kidneys ... ... 827 



Heart 792 



Nerve 780 



Spleen ... ... 758 



Muscle 757 



Sweat 995 



Saliva 995 



Tears 982 



Brain 750 



Skin 720 



Bone marrow ... 697 



Liver 693 



Cartilage ... ... 550 



Gastric fluid ... 973 



Milk 891 



Fat 299 



Bone 216 



Ivory 100 



Enamel of tooth , 2 



Bile 864 



Blood 791 



The supply of water to the system is introduced in various ways, but 

 the larger proportion is taken in the form of liquid or solid food, and there 

 is also a certain quantity of water formed in the system by the oxidation of 

 the various organic substances, resulting in combinations of oxygen with 

 hydrogen and carbon producing water and carbonic acid. 



Considering the important uses to which water is destined in the animal 

 organism, it is remarkable that there is so little positive evidence of the 

 injurious results attending the consumption of water which is polluted w r ith 

 animal and vegetable matter in various states of decomposition, with leak- 

 age from drains, with constant admixture with animal excreta, with the gases 

 which are given off from decomposing bodies, and also with the organisms 

 of specific diseases. It is quite true that every now and then the public is 

 startled by a record of a great outbreak of typhoid fever or other fatal 

 disease in consequence of some accidental contamination of the water- 

 supply; but, as a rule, polluted water is about the last thing which is 

 thought of as a possible cause of the outbreak of disease. This indifference 

 probably arises in a great degree from the knowledge of the fact that 

 people and animals continue to use the water of wells which are so placed 

 as to be open to the entrance of the overflow of cess-pools; or, in cases of 

 great scarcity, water from roadside ponds or ditches which are open to 



