138 INSECTS AND MAN 



just opposite, is also immune. Murano, close by, with its 

 industrial population of world-famous glass-blowers, is 

 also quite free. The islands that harbour pellagrins are 

 Pellestrina and Chioggia between Lido and the mainland 

 to the south, where the Brenta and the Adige flow out into 

 the sea, and the group of islets formed by Burano, Torcello, 

 Mazzorbo, S. Erasmo, etc., between Lido and the mainland 

 to the north about the mouth of the Piave. Both the 

 Pellestrina and the Burano group of islets are inhabited 

 principally by fishermen, who fish in various parts of the 

 lagoon, and not infrequently, especially in the spring, for 

 weeks together, along the mainland coast. Burano is a 

 small islet entirely covered by closely clustered houses. 

 As a town one would naturally expect it to be entirely 

 free from pellagra, just like the neighbouring Venice and 

 Murano, yet many of its inhabitants are pellagrins. But 

 whilst on the neighbouring mainland and in all pellagrous 

 districts throughout the world the disease is, as a rule, 

 more prevalent among women than men, the Burano 

 pellagrins are almost exclusively men. Moreover, whilst 

 on the mainland the disease is especially common in very 

 young children, in Burano it has never been known to 

 occur in any girls, and only very rarely in boys, and not 

 before their tenth year. Another interesting and telling 

 fact is that, whilst the disease is very common amongst the 

 fishermen, it has never been seen in any of the Burano 

 artisans who go every day to work at the Venice arsenal. 

 It is obvious, therefore, that Burano is not an endemic 

 centre, and that its fishermen, who are very heavily taxed 

 by the disease, contract it whilst fishing along the main- 

 land coast, and especially near the mouths of the Brenta 

 and other streams flowing into the lagoon, when they are 

 at times greatly molested by swarms of small biting flies. 

 This explains why, contrary to the general rule, the 

 disease in this island is restricted almost entirely to adult 

 males and to the older boys who go out fishing with their 



