HEREDITY IN PHYSIOLOGY, IN MEDICINE, ETC. 331 



theoretical exposition and of pictured conception are pre- 

 cisely the ones best understood on their practical side. 

 Familiarity with effects seems in these cases unavailing to 

 gain any understanding of causes. 



These reflections have a particular application to he- 

 redity. The fact exists that the ovule contains in its sub- 

 stance, seemingly homogeneous, not simply the anatomical 

 organism of the individual about to issue from it, but, more- 

 over, his temperament, character, capacities, his thoughts, 

 and his feelings. The parents lodge in that molecule the 

 future of an existence almost always identical with their 

 own from the physiological point of view, often so in re- 

 spect to the pathological one, and wholly so in many in- 

 stances when psychologically regarded. We propose to 

 bring to our readers' knowledge the results of the latest 

 researches on the subject of that amazing work of vital 

 economy. 1 



I. 



Heredity is that biological law in virtue of which living 

 beings incline to transmit to their progeny a certain por- 

 tion of the traits which characterize themselves. It is a 

 very delicate problem to decide whether we are to attrib- 

 ute to heredity the handing down of the anatomical forms 

 and the physiological functions of that species which is 

 represented in the particular system. At all events, in this 

 respect it is plain that the reproduction of parents in their 

 children is thorough and absolute ; otherwise there would 

 be no such thing as species ; there would be mere succes- 

 sions of beings, with no other relations to each other than 

 that of generation. Within our experience, as limited by 

 history, the constant new production of specific characteris- 

 tics, always identical, in other words, the permanent integ- 

 rity of species, is a fact almost beyond dispute. Such 



1 See particularly Th. Ribot, " Heredity, its Phenomena, its Laws," 

 etc. Paris, 8vo, 1873. 



