154 CURIOUS PROBLEMS IN 



vora, have not that power over herbivora. Cattle in marsh-lands 

 seem indifferent to the marsh-poison, and so do dogs ; but indi- 

 viduals of the same species, if newly brought into the district, 

 become infected. An analogous case occurred last year in 

 France, where a Parisian family, going into a provincial district, 

 were warned not to drink the water from a certain well. The 

 well was innocuous to the inhabitants of the village, but " gave 

 fever to strangers." The Parisian visitors were careful to avoid 

 the water during their stay, but on the last morning, thinking 

 possibly that " only once " wouldn't matter, they drank water 

 from the affected well, and on their return to Paris all suffered 

 more or less from typhoid fever. 



A most strange case is that of the tsetse fly of South Africa, 

 which is only fatal to domestic animals, such as the domestic ox, 

 horse, and dog, while the buffalo and the zebra, bitten at the 

 same time_, remain unharmed. Man is bitten, but does not 

 suffer. Neither do dogs reared wholly on game, but if fed on 

 milk they die. Yet all young sucking animals are safe so long as 

 they suck only ! Inoculation is no defence, nor any length of life 

 in the district. The resistance in the negro races to yellow fever 

 is well known, whether they are inland or coast-bred, and is 

 transmitted by them to their mixed progeny. On the other hand, 

 the poison of veri-veri does not attack Europeans until they have 

 lived in the district for some time ; but they finally become liable 

 to attack. But for all Aryans — Europeans and Hindus, branches 

 of a race which have been widely separated since before the 

 earliest historical period — the death-rate from veri-veri is low. 

 For Chinese the average death-rate is 51 "9, whilst for the Euro- 

 pean it is 28-6, and for the Hindu 27-8. 



It is rather startling to find that the superior vitality of black 

 pigs has a parallel in the superior vitality of the darker races of 

 man in many parts of Western Europe. The aboriginal mongo- 

 loid race of Europe was in all probability easily conquered by 

 force of arms, and in many districts almost exterminated, by the 

 Aryan immigrants, whether these latter came originally from the 

 north or from the east. But the proportion of dark-eyed, dark- 

 haired persons is steadily increasing in Germany — so steadily, 

 indeed, that it is doubtful whether the golden-haired, blue-eyed 



