unstable, consequently there is an inherent failure to control its conversion 

 into active energy as in epilepsy and other paroxysmal nervous states. 



The discovery of Mendelism has opened up a new and vast field of investi- 

 gation, and although so far Mendelian analysis is as yet imperfectly developed 

 in respect to human inheritance, yet as Bateson says : " Organisms may be 

 regarded as composed to a great extent of separate factors, by virtue of 

 which they possess their various characters or attributes. These factors 

 are detachable, and may be recombined in various ways. It thus becomes 

 possible to institute a factorial analysis of an individual." How far such 

 analysis can be carried we do not yet know, but we have the certainty that 

 it extends far, and ample indications in supposing that we should probably 

 be right in supposing that it covers most of the features, whether of mind or 

 body, which distinguish the various members of a mixed population like that 

 of which we, form a part. From such a representation we pass to the 

 obvious conclusion .that an individual parent is unable to pass on to off- 

 spring a factor which he or she does not possess. Since thqse individuals 

 only which are possessed of the factors can pass them on to their offspring, 

 so the offspring of those that are destitute of those elements do not acquire 

 them in subsequent generations, but continue to perpetuate the type which 

 exists by reason of the deficiency. It should be explicitly stated, however, 

 that in .the case of the ordinary attributes of normal men we have as yet 

 unimpeachable evidence of the manifestation of this system of descent for 

 one set of characters only, namely, the colour of the eyes. Moreover, 

 if the evidence as to normal characteristics of man is defective which in 

 view of the extreme difficulty of applying accurate research to normal 

 humanity is scarcely surprising there is in respect of numerous human 

 abnormalities abundant evidence that a factorial system of descent is 

 followed." (Bateson: Biological Fact and the Structure of Society.) 



This may be, as Bateson claims, true for certain well defined abnormali- 

 ties, e.g., polydactylism, brachydactylism, xeroderma pigmentosa, or 

 for night blindness, but as applied to the inheritance of a diathesis or 

 tendency, e.g., the neuropathic, Mendelian proportions are not shown as a 

 rule, although there is evidence of segregation of the factor underlying the 

 diathesis or tendency. 



With this brief introduction to my subject, allow me to consider the 

 problem of Heredity and Eugenics in relation to insanity. Let me first 

 define my terms : Heredity has been defined by Thomson as*" the genetic 

 relation between successive generations, and inheritance includes all that the 

 organism is or has tQ^start with in vktii^HtS~""rieTe~ditary relation; r> 

 Heredity is a relation in successive generations which is sustained by^X 

 more or less visible material basis, the germinal substance. i.Eugenics_is 

 the science of racial improvement by the application of ihe laws p* 

 heredity, viz., by encouraging the survival and the propagation of the 

 fittest in all classes of society, and by seeking to cut off the lines of 



