64 
Water, like other bodies, expands by heat and contracts by 
cold. But at one particular point there is an exception to. 
this rule. At the temperature of 40 deg. Fahr., water is at its 
greatest density, and as each degree of heat is lost it eapands, 
and so rises. It is thus that the temperature of 32 deg.— 
the point at which water becomes solid—is always the top 
layer—and ice is formed at the surface. If it were other- 
wise, many of the rivers and lakes of the world would ages 
ago have become solid masses of ice, and a large portion of 
the world a region of desolation and death. But, thanks to 
this exception to a general law, it is not so. 
Whence this exception? Did the particles of the fluid 
impress it upon themselves? If so, they must be credited 
with doing that which bears the mark of Intelligence. 
Take another example—the arrangement for maintaining 
the proper proportion of the constituents of the atmosphere. 
The atmosphere is composed of gases mechanically mixed. 
Nitrogen 77 parts, oxygen 23,* and a varying amount of 
watery vapour. The world of organization is made up of 
vegetables and animals. The plants are makers: and if they 
had a voice their constant cry would be, ‘‘ Give us carbon.” 
Animals are consumers, and if they had a voice their cry would 
be, “ Give us oxygen.” Now, how are the wants of each class 
supplied? Thus :— 
The main substance of plants is carbon. In order that the 
tissues may be built up carbon must be supplied; and as 
plants obtain their nourishment by absorption, the carbon 
must be supplied in a gaseous form. 
The chief product of respiration of animals is carbon di- 
oxide. Carbon, taken as solid food is the chief supply, and 
this, after the processes of digestion and absorption, as blood 
comes into contact with air in the lungs, unites with the 
oxygen, and forms carbon di-oxide, which is exhaled. 
Plants imbibe the air charged with carbon di-oxide, decom- 
pose it, and turn it into carbon and oxygen, keep the carbon, 
and return the oxygen to the air, to be again used by animals. 
There: is thus a constant interchange, and the balance is 
maintained. Whence this arrangement? Did the plants and 
animals arrange it for themselves? If so, they must be 
credited with wisdom, power, and benevolence. 
According to the hypothesis of Evolution, the only animals 
that existed at first were certain low forms of the Protozoa, - 
* Percentage of Oxygen, by weight, 23. Nitrogen, by weight, 77. 
Ditto, by volume, 21. Do., by volume, 79. 
Watts’s Chemistry, vol. i., p. 431. 
