290 THE SCOTTISH NATURALIST 



down much longer and coarser than the other and of a 

 different colour. To this special growth the term " nest 

 down " is applied, and we are given to understand that it 

 alone is " used for embedding the eggs in during incubation." 

 This is most interesting, and brings to our recollection the 

 fact that years ago, when considering methods for the 

 identification of ducks' eggs, we found that the down on a 

 duck shot in winter did not agree with samples taken from 

 nests of the same species. The subject is deserving of 

 further study, and some apparent discrepancies between 

 Miss Jackson's descriptions of certain "nest downs" and 

 those given by Heatley Noble and others seem to require 

 explanation. 



Dr R. Dods Brown, Physician Superintendent of James 

 Murray's Royal Asylum, Perth, has just published ^ an 

 interesting summary of the state of our knowledge regarding 

 the disease known as " pellagra." This malady was, up to a 

 few years ago, believed to be found principally in the south 

 of Europe, and not known to occur in Great Britain. It is 

 now evident that it is not uncommon in the British Isles, and 

 the author saw two cases in Perthshire in 1914. Many 

 theories have been advanced as to the causation of pellagra, 

 but evidence is steadily accumulating in support of the belief 

 that some species of sand-fly or Simtdium acts as a carrier of 

 the organism which produces the disease. As is well known, 

 the larvae of Siviulium inhabit clear, rapid streams, while it 

 has been found that pellagra is confined to well-defined areas 

 in which such a stream is present. Several species of 

 Simuliuni are common in Scotland, and it is probable that 

 in the near future a good deal may be learned in our hilly 

 districts of the real connection between these flies and a 

 disease which undoubtedly occurs, and which has hitherto 

 been erroneously diagnosed. 



' Review of Neurology and Psychiatry^ July 19 15. 



