696 REPORT— 1903. 



seconds later. On going out at once with a net a sample of the plankton wag 

 obtained, but it was not certain that any of the pulsating forms had been caught. 

 The gathering contained Sagittn (very many), Ap2)endicularia, Copepoda, several 

 common species and Sapphirina sinuiccmda, Pontella /era, Calocalnnus pavo, 

 and some smaller forms, along with half-a-dozen one-inch-long Heteronereids of 

 a reddish-brown colour. The light was tlioiight to be probably due to the last 

 named, and if that is so possibly the periodicity was a result of the epitocous 

 condition, and was accompanied by a simultaneous discharge of genital products. 

 The matter, however, could not be made certain at the time, and the above 

 explanation is only suggested. 



3. I^ote on Birds noiv rare in the British Isles. 

 By G. P. Hughes, F.R.G.S. 



The author gave a brief account of a male and female Bittern shot at the base 

 of Cader Idris last winter, and of a Common Crane he lately saw in the valley of 

 St. John, Isle of Man, species now rare in the British Isles. 



4. Demonstration of Visual Combination of ComplemeyUary Colours. 

 By C. A. Greaves, M.B., LL.B. 



The author showed that the difliculty in visually combining different colour 

 sensations so as to perceive the resultant is overcome in the case ot green + red = (/rey 

 by the use of the present halfpenny and penny stamps, stereoscopically super- 

 posed, these stamps being identical in design and of good complementary colours. 



5. Tlie Epithelial Islets of the Pancreas in Teleostei, 

 By John Rennie, D.Sc. 



It has been found that in all the leading divisions of this group there exist 

 in more or less intimate relation to the pancreas epithelial bodies similar to the 

 ' islets' present in higher forms. In a large proportion of cases there is an islet 

 in the mesenteric fold anterior to the spleen, which is of constant occurrence. It 

 is also the largest. As similar constancy has not been made out for the others it 

 has been termed the ' principal islet.' These bodies are an epithelial tissue con- 

 sisting of masses of very small polyhedral or cylindrical cells well supplied with 

 blood capillaries. In many cases two types of cell are evident within the islet, 

 which may be two distinct tissues or the same tissue in different functional 

 states. A comparative study of their relations to the zymogenous tissue cf the 

 pancreas suggests that they are blood glands which have entered into a secondary 

 relation to the pancreas. It is likely that they maintain their primitive function 

 as glands possessing an internal secretion. 



G. On the Echinodermata of the Firth of Clyde and Variation in 

 Ophiocoma nigra. ^ By D. C. McIntosh, M.A. 



In this paper, which dealt with the Echinodermata of the Clyde area, notes 

 were given on the frequency of the occurrence of the different genera and on some 

 of the most obvious variations exhibited by certain of the species. The daily 

 dredging expeditions of the steam yacht ' Mermaid,' which is run in connection 

 Avith the West of Scotland Marine Biological Association Station at Millport, 

 afforded one ample opportunity for making the necessary observations. 



It was pointed out that while forty-two species are recorded for the Clyde 

 (against at least thirty-five for the Irish Sea), there were actually found during 



' Published in Biumetrika, vol. iv. 



