70 HEREDITY AND VARIATION 



Persistent Peculiarities in Families. Not less striking than 

 the long persistence of specific and stock characters is the fact that 

 offspring frequently reproduce the individual peculiarities both 

 normal and abnormal of their parents or ancestors. A slight 

 structural peculiarity, such as a lock of white hair or an extra 

 digit, may persist for several generations. A slight functional 

 peculiarity, such as left-handedness, has been recorded for at 

 least four generations, and colour-blindness for five. The strong 

 under-lip of the Hapsburgs persisted for six centuries. There are 

 endless illustrations of the fact that a pathological diathesis 

 rheumatic, gouty, neurotic, or the like may persist and express 

 itself similarly, even in spite of altered conditions of life, through- 

 out many generations. And what is true of bodily characteristics 

 is not less true of mental peculiarities : as to this, popular im- 

 pressions and the careful investigations of Galton and others are 

 in agreement. We think at once of cases like the Bachs, the 

 Bernouillis, the Darwins ! 



3- Different Kinds of Organic Change 



It may conduce to clearness if we think over the different 

 kinds of changes which occur in organisms. 



i. Metabolism. All living creatures are, as it were, whirl- 

 pools in the universal ocean of matter and energy. They are 

 continually changing as they live. Streams of matter and energy 

 pass in and out. Organisms are animate systems which transform 

 matter and energy in a characteristic way which we call living. 

 Their physical basis is continually undergoing disruption and 

 reconstruction ; it breaks down and is built up again, it wastes 

 and is repaired, it runs down and is ever being wound up again 

 until the arrears of imperfect recuperation become so serious that 

 the organism dies, or until some fatal accident occurs. The 

 chemical and physical changes involved in living are summed up 



