RECIPROCAL INFLUENCE OF ANIMALS. 635 
distance of several hundred English miles, that the survivors 
were unable to bury the dead.* * * § 
Livingstone affords us a noteworthy example of people in 
South Africa, who were unaffected by disease, being the cause 
of its outbreak in others with whom they chanced to come in 
contact. The Boers under Potgeiter visited Algoa Bay for 
the first time about ten years ago, in order to secure a port 
on the east coast for their republic. They had come from a 
part of the interior where the disease called croup occasion¬ 
ally prevails. There was no apjyearance of the disease amongst 
them at the period of their visit, but the Portuguese inhabit¬ 
ants of that bay found they had left it among them, and 
several adults were cut off by a form of the complaint called 
‘ laryngismus stridulus,’ the disease of which the great 
Washington died. Many of the inhabitants here were cut 
down, usually in three days from their first attack, until a 
native doctor adopted the plan of scratching the root of the 
tongue freely with a certain root, and giving a piece of it to 
be chewed.” t 
Nearer home we have a similar instance of the influence of 
proximity in the case of the people of St. Kilda, a small 
island lying off the Scottish coast, and inhabited by some 
thirty or forty poor families, who hut rarely hold communica¬ 
tion with the mainland. It is asserted, that on the arrival of 
a stranger all the inhabitants, in common phraseology,‘‘catch 
a cold.” Nearly every year there is an epidemic catarrh fol¬ 
lowing the presence of visitors from the adjacent coast. J 
The effects of overcrowding of men and animals are well 
known. Maladies of various kinds, oftentimes of a conta¬ 
gious character, become rife and fatal among them. Even 
when apparently healthy themselves, organisms which have 
been submitted to these influences have not unfrequently 
become agents in the transmission or generation of these 
diseases. Many instances are related, but the following occur¬ 
rence, told by Darwin,§ is a remarkable illustration. In the 
early part of the reign of George III, a prisoner who had 
been confined in a dungeon was taken in a coach with four 
constables before a magistrate, and although the man himself 
was not ill, the four constables died from a short putrid 
fever, but the contagion extended to no others. “ It would 
almost appear,” continues Darwin, “ as if the effluvium of 
* Drake, ‘ Hist, and' Antiq. of the City of Boston,’ p. 30. 
j- ‘ Journeys,’ &c., p. 6J9. 
f Macculioch, ‘Western Isles,’ vol. ii, p. 32; Pennant, ‘Travels in 
Scotland.’ 
§ Op. cit., p. 521, 
