MALFORMATIONS AND THE LIKE 287 



though there is always some uncertainty. Of twins, one may be 

 infected and the other not. But the chances are so many that a 

 patently syphilitic father will have syphilitic or in some way deterio- 

 rated children, that the marriage of a patently syphilitic subject 

 can only be called a crime — the more heinous since the disease in 

 the offspring is often more serious than in the parent. It seems, 

 furthermore, certain in the case of this disease that, apart from 

 the specific ante-natal infection of offspring, the toxins produced 

 by the microbes in the body of the parent or parents may induce 

 general disturbance or debility of constitution in the germ-cells, 

 and thus result in inferior offspring. 



§ 7. Dejects, Multiplicities, Malformations, and other 



A bnormalities 



For convenience, though we are here passing away from disease, 

 we may include in this chapter a few references to the inheritance 

 of abnormalities in the wide sense. 



(a) Defects. — There are many cases on record where an absence 

 or deficiency of a particular structure has persisted for several 

 generations. Some of these minus variations have been utilised 

 by man as the origin of new domesticated breeds. It is enough 

 to mention hornless cattle — e.g. Polled Angus ; earless sheep — 

 e.g. of Syria and China ; tail-less cats — e.g. of Japan and the 

 Isle of Man ; short-tailed dogs and pigs. Such cases must be 

 distinguished from others quite different in nature, where a part 

 is absent through mechanical constriction during development, 

 and then, of course, no inheritance is to be looked for. 



Albinism or absence of pigment is frequently inherited in 

 man. 



Sir William Turner gives a rather striking case where a shorten- 

 ing or imperfect growth of the metacarpal bone of the ring-finger 

 of the left hand " was traceable throughout six generations, 

 and perhaps even in a seventh, and was, as a rule, transmitted 

 alternately from the males to the females of the family." 



In a family in Pennsylvania described by Farabee many of the 



