51 



bj staining, but with the advantage that a harmonious appearance was 

 always produced, whereas with staining the selective power caused differ- 

 ences of colour which were not always harmonious. 



Mr. Stewart said he had not made any researches into polarized light as 

 applied in this oblique direction ; it appeared, however, that it might be 

 advantageous, but without having experience of its working it was exceed- 

 ingly difficult to say much about it. He wished to inquire what was the 

 position of the selenite ; he presumed that it was put with its plane parallel 

 to that of the object. 



Mr. Michael said it was placed in the ordinary way. 



Dr. Matthews said that he had made some sections of ovaries of plants 

 which proved to be too thin to produce any effect. He afterwards gave 

 them to Mr. Ingpen, who he believed could get no coloured effects from 

 them ; he should like Mr. Stewart to see them. So far as he had tried, no 

 selenite thick or thin would differentiate them on the black ground. 



Mr. Stewart thought this would probably be owing to the very slight 

 tension in the cells; in the ordinary thickened cells they would be much 

 more likely to get colour than in rapidly built cells such as those of 

 the ovaries. The most delicate colour to use for such a purpose would be 

 the blue of the third series, which was rather difficult to obtain ; it was a 

 blue the value of which consisted in the fact that a very slight difference of 

 thickness would replace it by emerald green or red, so that a very slight 

 degree of tension would suffice to produce colour effects. 



Mr. Ingpen said he put the specimens mentioned by Dr. Matthews under 

 his microscope in polarized light ; he could not use the particular selenite 

 which had been referred to, but he failed to obtain any effect with these thin 

 sections, though with thicker sections he got a similar effect to that which 

 Mi\ Stewart had described. He was in favour of mounting vegetable 

 tissues in glycerine. He had mounted many in glycerine jelly, and with 

 that medium he obtained a very delicate reaction. 



Dr. Matthews said he had found this method very useful in examining 

 morbid tissues ; in looking at a specimen of epithelioma he found that the 

 cells showed the black cross as in the starches. 



Mr. Stewart said that the only conditions necessary to show the black 

 cross were to have lines of strain either radiating from the centre or run- 

 ning concentrically ; it did not matter what the nature of the structure was 

 so long as these conditions existed ; so that if they had epithelial cells 

 either wrapped round a cylinder or radiating from a point, they would get 

 this effect at once without doubt. Mr. Stewart then, by means of black- 

 board drawings, explained more fully the production of the black cross in 

 the two ways referred to. 



The thanks of the meeting were unanimously accorded to Mr. Michael, 

 Dr. Matthews, and Mr. Stewart for their remarks. 



Mr. J. D. Hardy exhibited and described an improved Compressorium. 



The President said there could be no doubt that this form of compressor 

 obviated the disagreeable squeezing-out so often complained of. 



Mr. Fox inquired what was likely to be the cost of it. 



