NATURAL HISTORY SOCIETY OF GLASGOW. V 



gathered by him in a small marsh on the east side of Knock- 

 ewart Hill, near Ardrossan, and made some remarks on the 

 distribution of the species. 



The Chairman (Mr. Cameron) exhibited specimens of several 

 species of Tenthredinidce, including Dineura stilata, King., a 

 species remarkable for the variation shown in the neuration of 

 the wings. He stated that the majority of the specimens found 

 have only one radical cellule, and are practically species of the genus 

 Nematus, this form having indeed been recently described as a new 

 species of Nematus by Brischke and Zaddach. The obliteration 

 of certain nervures appears to have been caused by the enlarge- 

 ment of blister-like spots, found in a more or less developed 

 state in most Tenthredinidce, and formed in all probability by 

 the manner in which the undeveloped wings were folded in the 

 pupa. As about 70 per cent, of the specimens of Dineura 

 stilata, Klug., have only one radical cellule in the fore wings 

 it is conceivable that in a comparatively short period all the 

 individuals will be in that condition, and will then require to 

 be transferred to the genus Xentatus, from which Dineura only 

 differs in having two radical cellules. From the point of view 

 of evolution, therefore, the species is of much interest, as it 

 shows how what we call "genera" have been formed, in this 

 case apparently by mechanical causes acting in an earlier stage 

 of the creature's existence. Mr. Cameron also exhibited a 

 Nematus bred from a green larva on the hawthorn, and appar- 

 ently identical with a species figured but not described by 

 Brischke and Zaddach under the name of Nematus crata^gl; 

 also living larvae of Nematus caddereiisis. Cam., from Fossil 

 Marsh, where they were found feeding on the leaves of SaJix 

 pentandra, their usual food being the leaves of the birch. 



Mr. William Goodwin read a paper on *' Double-staining 

 Vegetable Tissues." After referring to the various methods of 

 preparing tissues by the double-staining process, he described 

 fully the system of manipulation which he had found to l)e 

 most practicable. When the sections had been cut, they could 

 be preserved for a considerable time if kept immersed in spirit 

 diluted with water. The first step in the process was bleaching. 

 Sections which were little coloured might be bleached by im- 

 mersion in spirits of wine, but if more highly-coloured it was 

 necessary to treat them with a chlorine solution, the well- 

 known "ozone bleach" being well adapted for the purpose. 

 They must afterwards be thoroughly washed, otherwise they 

 would gradually fade after having been dyed; and when 

 perfectly free from the chlorine solution they might be put 

 into a weak spirit until ready for the next process, which 

 was dyeing with carmine. Before dyeing it was necessary to 

 use a mordant — a five-per-cent. solution of acetate of alumina 



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