SOCIAL AND WORLD ASPECTS 217 



This condition of cretinism is said to be constantly 

 associated with placental disease, which would pre- 

 vent the thyroid hormones of the mother from acting 

 properh' upon the young. The frequent occurrence 

 of cretinism in this breed of cattle may, then, perhaps 

 be accounted for by a diseased placenta preventing 

 the already hypothyroid mother from furnishing her 

 offspring with sufficient thyroid secretion. There is 

 another explanation, however, which appears more 

 probable. In at least one case a cow is known to 

 have produced a normal calf following a cretinous 

 one. Any defect in the placenta would then probably 

 not be the result of a diseased condition of the cow, 

 but rather the initial defect would be in the developing 

 foetus. Another fact which may be significant is the 

 occurrence of 25-4 per cent, of " cretinous " offspring 

 in the larger herd already referred to. This clearly 

 suggests that the condition is a Mendelian recessive, 

 due to a lethal mutation carried in the germ plasm 

 of the breed, or in some of them. Further data would 

 be required in order to verify this h^'pothesis. 



Sir Arthur Keith applies the same conceptions of 

 hormone determination to the anthropoid apes and 

 other vertebrates, holding that in the orang there is a 

 predominance of thyroid, while in the gorilla the 

 pituitary is predominant. However this may be, the 

 view seems well founded that raciiil differences in 

 man, including the colour and character of the skhi 

 and hair, differences in physiognomy and in stature 

 and the relative length of limbs, are related to inherited 

 differences in the activities of various endocrine 

 glands. This thesis will, no doubt, be further 

 elaborated with increasing knowledge. 



The bodily changes associated with pain, fear, and 

 rage have been particularly studied by Cannon (191 6), 

 who showed how in a state of fear or anger adrenahn 

 is poured into the blood, which causes reactions, 



