ON HEREDITY. 549 



strongly shown, and occnrs in from 50 to 75 per cent, of the cases ; 

 further, that the chihlreu of gouty parents show signs ofarticuhir gout 

 at an age when they have not assumed those habits of life and peculi- 

 arities of diet whicb are regarded as the exciting causes of the disease. 



In connection with the tendency to the transmissibility of either con- 

 genial malformations or diseases, consanguinity in the parents, al- 

 though by no means a constant occurrence, is a factor which in many 

 cases must be taken into consideration.* If we could conceive both par- 

 ents to be physiologically perfect, then it may be presumed that the off- 

 spring would be so also ; but if there be a dej)arture in one parent from the 

 plane of physiological perfection, then it may safely be assumed that 

 either the immediate offspring or a succeeding generation will display 

 a corresponding departure in a greater or less degree. Should both 

 parents be physiologically imperfect, we may expect the imperfections, 

 if they are of a like nature, to be intensified in the children. It is in 

 this respect therefore that the risk of consanguineous marriages arises; 

 for no family can liiy claim to physiological perfection. 



When we speak of tendencies, susceptibilities, proclivities, or i)re- 

 disposition to the transmission of characters, whether they be normal 

 or pathological, we employ terms which undoubtedly have a certain 

 vagueness. We are as yet quite nnable to recognize, by observation 

 alone, in the germ-plasm any structural change which would enable 

 us to say that a particular tendency or susceptibility will be manifested 

 in an organism derived from it. We can only determine this by fol- 

 lowing out the life-history of the individual. Still it is not the less true 

 that these terms express a something, of the imi^ortauce of which we are 

 all conscious. So far as man is concerned, the evidence in favor of a 

 tendency to the transmission of both structural and functional modifi- 

 cations which are either of disservice or positively injurious, or both, 

 is quite as capable of proof as that for the transmission of characters 

 which are likely to be of service. Hence useless as well as useful char- 

 acters may be selected and transmitted heriditarilj. 



Much has been said and written during the last few years of the trans- 

 mission from parents to offspring of characters which have been '* ac- 

 quired" by the parent, so that I cannot altogether omit some reference 

 to this subject. It will conduce to one's clearness of perception of this 

 much-discussed question, if one defines at the outset in what sense the 

 term " acquired characters" is employed ; and it is the more advisable 

 that this should be done, as the expression has not always been used 

 with the same signification. This term may be used in a wide or in a 

 more restricted sense. In its wider meaning it may cover all the char- 

 acters which make their first appearance in an individual, and which 

 are not found in its parents, in whatever way they have arisen: — 



(I) Whether their origin be due to such molecular changes in the 



"1 may esi>ecially retVi- (for a discussion of this subject) to an admirable essay l>y 

 Sir Arthur Mitchell, K. C. B., "On Blood-relationship in Marriage cousidered in its 

 Intluence upon the Offspring." 



