THE INHERITANCE OF FAMILY TRAITS 107 



times called poltering. A case of it occurs in three genera- 

 tions and is given by Berkan (Fig. 72). The peculiarity is 

 found in each of three generations; it may of course be as- 

 sisted by imitation. 



Lolling is speech in which the articulatory mechanism is 

 not used with precision, as in young children. There is 

 some evidence that this defect may be a family one. Thus 

 r^kloyer (1893) records a family in the first generation of 

 which there were a normal sister and three brothers; one 

 who was quite normal in speech, one who did not learn to 

 speak until 6 years old, and one who lolled his life long. The 

 latter had 6 children, all normal save one who lolled. The 

 other affected brother had 12 children of whom, however, 

 5 died in infancy, lea\ing 7. Of his four daughters one had 

 ^defective utterance, while all three boys were defective in 

 speech, although after puberty the defect gradually dis- 

 appeared. One of these boys has 3 sons, all normal. The 

 case illustrates segregation but hardly suffices to demonstrate 

 the law of inheritance of the pecuharity. 



27. Defects of the Eye 



Apart from albinism, the effects of which are most strongly 

 felt in the increased sensitiveness of the retina to strong light, 

 the chief optical defects whose inheritance has been studied 

 are as follows; (a) absence of or defect in the iris and dis- 

 placement of the pupil; (b) reduction in size of the whole eye- 

 ball to complete absence; (c) atrophy of optic nerve; (d) 

 cataract; (e) dislocation of the lens; (f) degeneracy of the 

 cornea; (g) glaucoma or excessive production of fluids of the 

 eye; (h) megalophthalmus, or big eye; (i) nystagmus or 

 "swimming eye;" (k) paralysis or imperfect development of 

 muscles of the eye and Hds; (1) pigmentary degeneration of 

 the retina (retinitis pigmentosa) ; (m) night bhndness (hem- 

 eralopia); (n) colorblindness; (o) astigmatism; (p) myopia. 



