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been produced. The effects of this great law have been 

 recognised and appreciated from the earliest ages ; and, 

 while the axiom of Lamarck that " like produces like " may 

 be true as a generalization, yet the tendency to variation 

 which is manifested in all animals as resulting in the 

 differentiation of individuals is so potent as to frustrate 

 the attainment of the ideal law. 



The office of Science consists in the interpretation of 

 natural laws, by means of the study of phenomena in rela- 

 tion with experience. Heredity is a physiological necessity 

 of our being inseparably connected with reproduction, and 

 the mysterious source of both may be traced to the fusion 

 of the sperm and germ cells, resulting in a germinal vesicle. 

 Analysing the human organism somewhat in detail, it is 

 found that the likeness between parents and children, 

 although by no means absolute, characterises not only every 

 element of their form, features, and expression, but also 

 every action, every function of their physical being, exten- 

 ding even to the transmission of idiosyncrasies, habits, and 

 acquired modifications, so that every anatomical conforma- 

 tion every physiological function and process the varieties, 

 and the minutest peculiarities of the individual in structure, 

 composition, and properties, are alike found to be subject to 

 the grand law of heredity. 



The correlation and interdependence of the laws of 

 heredity and variability are well recognised in the great 

 evolutional theory of Darwin; and the so-called laws of 

 heredity, under which all the main facts are usually grouped, 

 may be thus briefly formulated : 



(1) Direct Heredity. 



(2) Reversional Heredity or Atavism. 



(3) Collateral or Indirect Heredity. 



(4) The Heredity of Influence. 



(5) Specialised or Initial Heredity. 



