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Note on Abnormal Pigmentation of a Whiting infected by 



Trematode'/aruce. 



By 

 Prof. F. W. Gamble, F.R.S., and G. H. Drew, B.A., Beit Memorial Fellow. 



In one of the tanks at the Plymouth Laboratory containing pipe-fish 

 and sticklebacks, a whiting was found recently which exhibited black 

 specks scattered over its pigmented areas and on the conjunctiva. 

 The spots were fairly evenly distributed and averaged '5 to •! mm. in 

 diameter. Around each black point there was a clear unpigmented 

 area. 



Preparations showed that this abnormal colouration was due to a 

 Trematode. Each black spot contained a cyst within which the para- 

 site lay. The influence of the parasite has drawn towards the cyst 

 all the neighbouring chromatophores, thus explaining the dense 

 accumulation of pigment in each spot and the area of pallor surround- 

 ing it. 



The Trematode is a species of Holosto rimm , probably H. cnticola, v. 

 Nordmann ; for that author described a similar infection in German 

 Cyprinoids as long ago as 1832. The points of interest are the 

 presence of this Trematode in British waters, the reaction of the 

 chromatophores, and the migration of pigment-cells into the con- 

 junctiva. 



January IS, 1911. 



