very striking way, only one person perhaps in a generation 

 is struck by it. ... In all these cases, however, it is proper 

 to take due account of the before-mentioned fact, that a 

 disease-tendency which is latent or dormant at one period 

 of life, or throughout the whole life of the individual, may 

 undergo actual development at a particular physiological 

 epoch, or an occasion of a great bodily crisis from some 

 other cause (almost at the same time in twins, sometimes) ; 

 and that a tendency which is latent or dormant in one 

 generation may show itself actively in the next generation. 

 Herein we recognise the pathological parallel of the physio- 

 logical dormancy of qualities which was previously taken 

 notice of; disease-tendencies, like parental characters of 

 mind and body, are held in check or actually neutralised." 



In approaching the consideration of those diseases in 

 which heredity is an especial factor, I purpose to allude 

 briefly to those diseases frequently occurring during uterine 

 existence, in the brief first stage of life of the unborn; 

 and, in the first place, it may be mentioned that some 

 writers make a distinction between what they term innate 

 diseases and those which are hereditary. The former may 

 be defined as those diseases with which neither of the 

 parents were affected, but were acquired by the foetus during 

 its stay in the uterus, in consequence of outward noxious 

 influences which operated upon it through the mother, 

 without creating in her a disease similar to that which 

 manifests itself in the child after its birth. These influ- 

 ences may be of a mechanical nature, such as pressure, a 

 thrust upon the pregnant uterus, or of a dynamic or 

 psychical kind. One or other of such influences, as also 

 bad regimen of the mother during pregnancy, is very likely 

 the cause of the so-called anomalies in the first formation, 



