GENERATION. 



471 



family the influence of the other parent, may 

 predominate.* 



Nor does it appear that any general law has 

 been established regarding the transmission of 

 the nature of the constitution, temperament, 

 state of health, duration of life, &c.; for in the 

 human species at least these qualities of the 

 offspring seem to be inherited from either 

 parent or from both indiscriminately. 



The complexion and colour of the offspring 

 has received much attention. In some animals 

 the colour of both parents is sometimes pre- 

 served, as in the piebald horse; in others a 

 mixture of the colours of the father and mo- 

 ther appears in the offspring as an interme- 

 diate tint. In other animals, and most fre- 

 quently in the human species, the colour de- 

 scends from one only of the parents. Thus 

 among white races of the human species, it 

 happens more frequently, when the parents are 

 of different complexion, that the child takes 

 after one or other of them than that its com- 

 plexion is intermediate between those of the 

 parents; but it does not appear as yet to be 

 ascertained that one parent determines the 

 colour more frequently than the other. The 

 offspring from the union of people of dark 

 and white races of the human species usually 

 has a complexion which is a mixture of or is 

 intermediate between the complexions of the 

 two parents, as in the Mulatto and other degrees 

 of colouring; but it is alleged that in these 

 instances the colour of the father usually pre- 

 dominates over that of the mother. Thus a 

 dark father produces with a white mother a 

 darker child than a white father with a dark 

 mother. Among animals there are infinite 

 varieties in this respect. White colour is 

 said to be more readily transmitted than others. 

 In some animals, however, colour is trans- 

 mitted with great regularity : thus it has been 

 found that as many as two hundred and five 

 of the product of two hundred and sixteen 

 pairs of horses of similar colour inherited the 

 colours of their parents. 



The degree of fruitfulness in bearing off- 

 spring, or the opposite, sterility, the qualities of 

 the voice, peculiarities in the degree of deli- 

 cacy of the external senses, as long or short- 

 sightedness, musical ear, &c., the physical 

 powers of the body as illustrated in the speed 

 or strength of horses, and peculiarities of the 

 digestive functions of the nature of idiosyn- 

 crasies, are other familiar examples of bodily 

 qualities usually transmitted in hereditary de- 

 scent from one or other parent to the offspring. 



Lastly, the qualities of the mind are, perhaps 

 as much as the bodily configuration and powers, 

 subject to influence from the hereditary in- 

 fluence of parents upon their offspring. The 

 powers of observation, memory, judgment, 

 imagination, the fancy, and all that belongs to 

 what is usually called genius, the emotions, 



* Dr. Walker, in a short essay lately printed for 

 private distribution, has attempted to shew that the 

 upper and back part of the head usually resembles 

 the mother, the face from the eyes downwards 

 most frequently the father. 



passions, desires, and appetites, as inborn 

 mental qualities of the offspring, are all liable 

 to be influenced in the act of generation by 

 the parents.* 



The hereditary predisposition of man and ani- 

 mals to particular diseases also illustrates in a 

 striking manner the general law now under con- 

 sideration, and from its importance in reference 

 to life assurance has attracted considerable at- 

 tention. 



Almost all the forms of mental derangement 

 are more or less directly hereditary, one of the 

 parents or some near relation being affected. 

 Of bodily diseases, pulmonary complaints, 

 diseases of the heart, scrofula, rickets, worms, 

 gout, rheumatism, hemorrhoids, hypochondri- 

 asis, scirrhus, apoplexy, cataract, amaurosis, 

 hernia, urinary calculi, may be mentioned as 

 examples of diseases more or less directly 

 transmitted as predispositions from parent to 

 offspring. The goitral and cretinous affections 

 combined with deficient intellect are striking 

 examples of the effect of hereditary influence 

 combined with that of the situation in which 

 the cretins live. The union of goitrous per- 

 sons in particular districts leads to the pro- 

 duction of cretins, while the union of a cretin 

 with a healthy person tends to the improve- 

 ment of the offspring, or its gradual return to 

 the healthy state. 



The predisposition to disease may be trans- 

 mitted to the offspring from either parent, and 

 from the one as often as from the other, but 

 much more certainly when both the parents 

 have been affected with the disease. 



We may also mention, in connection with 

 this subject, the transmission to the offspring 

 of various marks and deformities in the struc- 

 ture of the parents or their relations. The 

 cretinism already mentioned is one of these, 

 and there are numerous other cerebral de- 

 formities which are so transmitted, as congeni- 

 tal malformations, such as the acephalous and 

 anencephalous states, spinabifida,cyclopia, &c. 

 which run remarkably in particular families. 

 In many instances the hereditary cause of 

 these deformities has been distinctly traced to 

 one or other of the parents. Naevus, moles, 

 growths of hair in unusual places, hare-lip, 

 deficient or supernumerary toes or fingers, 

 have all been traced to hereditary influence, 

 and probably as often to the one parent or his 

 family as to the other. Malformations of the 

 heart, congenital hernia, and indeed most other 

 malformations, are capable of being traced to a 

 similar origin. 



Were further illustration of this general law 

 requisite, it would be found in the resem- 

 blance of mules or hybrids produced by the 

 union of two distinct races, varieties, or 

 species of animals, which productions also 

 afford an excellent opportunity of observing 



* In endeavouring to estimate the degree of 

 original resemblance of offspring to parent mentally 

 as well as bodily, but especially the former, great 

 caution is necessary not to overlook that resem- 

 blance between them which depends on education, 

 similar habits, pursuits, mode of life, and conti- 

 nual intercom se. 



