CLIMATOLOGY 



1597 



theory has not been supported by Fiilleborn's observations on Samoan 

 natives. Low, Grassi, Noe, and Fiilleborn, have suppHed the information as to 

 the method by which the Filaria escapes from the mosquito and enters man 

 during the act of biting. While, therefore, much has been done to elucidate 

 the nature of the lesions due to the worm, researches are still required with 

 regard to the method by which the worms produce the various pathological 

 phenomena attributed to them, especially elephantiasis, and the role of a 

 secondary bacterial infection in the production of the lymphangitis, abscesses, 

 and elephantiasis. 



The morbid anatomy has been investigated by but few observers, notably 

 by Mackenzie, Manson, Low, Young, and Bahr. 



Climatology. — ^The fact that ancient Indian writers were ac- 

 quainted with elephantiasis of the leg and scrotum, while Celsus 

 does not appear to have known the disease, and the further fagt^ 

 mentioned by both Hillary and Hendy, that elephantiasis was rare 

 in Barbados at the beginning of the eighteenth century, together 

 with Hillary's views that the disease was introduced into that 

 island by negro slaves from Africa, awaken suspicions that the 

 endemic home of filariasis is Asia, and that it has spread from thence 

 to Africa, and from Africa to America. If this gradual dissemina- 

 tion of filariasis is correct, it may explain many features of the 

 epidemiology which are difficult at the present time to comprehend. 



Be this as it may, filariasis is now widely distributed throughout 

 the tropics and the subtropics, extending from about 41° N. to 

 about 28° S. in the Eastern Hemisphere, and from about 31° N. to 

 about 23° S. in the Western Hemisphere. 



In Asia it is known in Arabia, India, Ceylon, Burma, Indo-China, 

 the Philippine Islands, Guam, China, and Japan. 



It is known in Australasia, especially in Queensland, and in 

 Oceania, especially in Fiji, in Samoa and the Friendly Islands, 

 but is absent in the Sandwich Islands. It is also known in New 

 Guinea. 



In America it occurs in the Southern United States, in Central 

 America, the West Indies, in Guiana, Venezuela, Brazil, Peru, and 

 Columbia. 



In Africa it is common on the West Coast, in South Africa, East 

 Africa, Madagascar, Reunion, Mauritius, Morocco, and Egypt and 

 Northern Africa. 



In Europe it is said to exist near Barcelona and in Turkey. 



In these countries its distribution is unequal, being in general 

 more common along sea-coasts and the banks of large rivers, but 

 presenting peculiar circumscribed endemic areas. Thus, Daniels 

 points out that in the Shire Highlands filariasis and elephantiasis 

 are only found in immigrants, while along the lower Shire River 

 both are common. 



Still more interesting is his observation that at the southern end 

 of Lake Nyassa there was only one case of filariasis met with, and 

 none of elephantiasis, while at the northern extremity both were 

 frequently seen. 



Low has also studied the distribution in the West Indies. Here, 



