522 
HEREDITARY DISEASES OF HORSES. 
several generations; and other analogous cases are recorded.* 
But the hereditary transmission of external form is exempli- 
fied, on a more extended scale, by the striking resemblance 
often observed amongst the different individuals of a com- 
munity or race, even where these are exposed to different 
external agencies. The cases of the Jews and the Gipsies 
will suggest themselves to every one as most apposite ex- 
amples. Although exposed for centuries to the powerfully 
modifying influences of external circumstances of climate, 
country, association with nations of very different customs 
and habits, these remarkable races still retain their identity, 
and remain distinct and peculiar people. But it is not alone 
their face or figure that remains unaltered, their manners, 
habits, and customs are also uniform and permanent : a most 
striking proof of the hereditary transmission of almost every 
bodily and mental character and quality. 
As regards intellectual ability, it is observed that certain 
races are remarkable for intelligence and aptitude in the 
acquirement of knowledge, and others for stupidity and nar- 
rowness of capacity ; that the children of such races, although 
reared and educated with equal care, always show much dif- 
ference in intellectual attainments ; and that it is only after 
educating several generations of the less-gifted race that they 
attain the natural capacity of the more gifted. Both ancient 
and modern history afford many striking instances of analo- 
gous temperaments and dispositions being transmitted from 
father to son through many generations; of some families 
remarkable during centuries for virtue, honour, and liberality, 
and of others notorious during an equally long period for 
every sort of wickedness, vice, and oppression. 
But diseases, as well as physical and mental qualities, 
descend from parent to children. Many of the most wide- 
spread and fatal maladies affecting the human subject are 
hereditary. Under this category we may include pulmonary 
consumption, which destroys so many of the inhabitants of 
these islands, frequently decimating, and sometimes com- 
pletely sweeping away, entire families ; scrofula, gout, gravel, 
and rheumatism, which, like consumption, occurs chiefly in 
predisposed subjects, and in the progeny of those w ho have 
themselves suffered from them ; most nervous diseases, espe- 
cially palsy, epilepsy, and insanity, which rarely attack any 
individual w ithout also affecting many of the same family ; 
* ‘ Researches into the Physical History of Mankind/ by James C. Prichard, 
3d edition, pp. 244-5. See also, at pp. 347-9, the description of a man whose 
skin was greatly thickened and covered with warty excrescences, and in whose 
descendants these peculiarities were noticeable in the third generation. 
