SECTION 23 GENERALISATION. 345 







but definite proportion, as illustrating the need of a high degree 

 of exactitude; the retardation of ascending missiles through 

 the action of gravity and their parabolic trajectory; the possi- 

 bility of a continuous transition from the liquid to the gaseous 

 state, as evidenced by gaseous carbon dioxide turning into its 

 corresponding liquid gradually; the difference in the penetrat- 

 ing power of alpha, beta, and gamma rays; the degree of 

 conductivity and compressibility of different substances; the 

 effect of variations in degrees of temperature in determining 

 the consistency of a substance or in producing the trade winds 

 and land and sea breezes; the problem of the pump, and of 

 the use of mercury in connection with the thermometer and 

 barometer ; the use of gold-leaf in electrical experiments because 

 of its unrivalled thinness; the quantitative and qualitative dif- 

 ferences between the chemical elements; the point of greatest 

 and least density of water and of other substances; steam, 

 cloud, mist, rain, hail, sleet, snow, ice, frost, and dew as 

 forms of water; the state of the earth now and when it was 

 in a gaseous condition; the similarity of the light seen when 

 the temperature of a meteorite is slowly raised in a laboratory 

 with that of a comet approaching the sun; the displacement 

 in geology of the catastrophic by the Huttonian theory; the 

 links which connect the lowliest with the most developed forms 

 of life; the relation of fluctuations to mutations in biology; 

 nerve cells, muscular cells, sense cells, and glandular cells, as 

 modifications of epithelial cells; the significant part played by 

 bacteria and earthworms in the economy of nature; the slow 

 forming and fading of sensory impressions; the problem of 

 attention and inattention, of habit and deliberate thought and 

 action, and of the formation of character ; the educative process 

 in the race and individual, and human progress from eolithic to 

 modern times and beyond; the relative moral, intellectual, and 

 hygienic effects of small and large potions of alcohol; the 

 ability to resist appreciable doses of poison through becoming 

 habituated to them by the frequent absorption of inconsiderable 

 doses; 1 the comparative truth and importance of two opposed 

 assertions or courses of action in politics or social life; the 

 slow development of landscape painting from still and dark- 

 green landscapes to landscapes abounding in colour and 

 movement, or portraiture from passivity and stiffness to action 

 and vivacity, of buildings from mud hut to Rheims cathedral, 

 and of music from the primitive man's chant to a Beethoven 



1 "It is only some fifteen years since Calmette showed that, if cobra 

 poison were introduced into the blood of a horse in less quantity than 

 would cause death, the horse would tolerate, with little disturbance, after ten 

 days, a full dose, and then day after day an increasing dose, until the horse, 

 without any inconvenience, received an injection of cobra poison large 

 enough to kill thirty horses of its size." (Sir Ray Lankester, The Kingdom 

 of Man, 1912, p. 79.) 



