SECTION 23 GENERALISATION. 361 



and yellow phosphorus into red phosphorus, and act upon photo- 

 graphic plates" (Thorpe, op. czY., vol. 2, p. 42), and "the mean 

 velocity with which the molecules of a gas move can be cal- 

 culated if we know the pressure it exerts, the weight of a 

 definite volume, and the value of the acceleration due to gra- 

 vity" (ibid., p. 71). 



Thus climatic changes, migrations, novel classes of food, 

 physiological adaptation, sexual selection, segregation, and other 

 factors, may severally be responsible for the trend of evolution, 

 as colouring in animate beings may be due to mimicry, or to 

 the value of protection, warning, and attractiveness combined; 

 the cause of criminality may be manifold exceptional tempta- 

 tion, bad companions, economic circumstances, faulty upbringing, 

 imperfect or no schooling, lack of vocation, unemployment, 

 alcoholism, poor health, and inferior intelligence; again, moral 

 conduct should be distinguished by all, rather than by one or 

 a few of, the powers of the mind being utilised, whilst only 

 he should be regarded as truly cultured who has highly de- 

 veloped all sides of his distinctive humanity, and not only some 

 sides; and that a subject or object should only be esteemed 

 adequately examined when every important relevant aspect is 

 taken into consideration. Again, reproduction is effected by 

 fission, budding, regeneration, hermaphroditism, and bisexually ; 

 and numerous elements have been gradually discovered in 

 the bodily constitutions carbon, hydrogen, oxygen, nitrogen, 

 sulphur, phosphorus, iron, sodium, potassium, calcium, mag- 

 nesium, chlorine, iodine, fluorine, silicon, and lithium. So, 

 too, climate should be conceived as dependent on proximity to 

 sea and mountains, position in regard to prevailing winds, 

 forests, deserts, watersheds, altitude, latitude, and configura- 

 tion and soil of a district, whilst the agents of denudation 

 should include, at least, rain, rivers, ice, frost, heat, the sea, 

 and wind. 



Accidents in factories are largely due to unprotected and in- 

 efficient plant ; to inexperienced, new, and ill-trained men ; to 

 bad tools and tools in bad condition ; and, of course, to fatigue, 

 indisposition, and carelessness. Types of men may be classed 

 as mental and manual, settled and roving, indoor and outdoor, 

 directive and dependent, minute and comprehensive, adapt- 

 able or self-satisfied, deliberate and impulsive, static and 

 dynamic. In fatigue we have to consider the draining of 

 energy, the accumulation of waste products, and the exhaustion 

 of nerves and of the central nervous system. The tests for 

 fatigue, again, are measurement of reaction time, of acuity 

 of sight and hearing, and of blood pressure. "Matter, what- 

 ever its origin, cannot be pronounced alive unless it is capable 

 of assimilating the unlike, of producing anti-bodies, of re- 

 producing itself, and of undergoing spontaneously a certain 

 degree of morphological differentiation." (D. Fraser Harris, 



