ii ASCENT OF SAP IN STEMS 33 



D was transferred to gelatine coloured with haematoxylin 

 at 50. 

 Each was immersed to a depth of 20 cm. and placed in 

 bright light, the air temperature being 16. At the expira- 

 tion of forty minutes all were transferred to water at 13. 

 Then the end of each was thinly pared, and at 5.30 p.m. 

 all were left finally standing in water at 13. At 6.30 all 

 were fresh. At 11 a.m. on the 10th, i.e., after 15j hours, 



A was still quite fresh, 



B ,, very much flagged, 



C ,, less flagged than B, 



D ,, ,, ,, B, but more nagged than 0. 



All were now transferred to a strong solution of saffranine, 

 and put in full sunshine for lj hours, when they were 

 washed and sections made for microscopical examination. 

 So far as C and D were concerned, it is only necessary to 

 observe that they revealed that only some of the lumina 

 were actually stopped with gelatine. The walls of many of 

 the gelatine -filled vessels were found stained with saffranine, 

 which attained to 26 cm. in C, and to 5 cm. in D. The gela- 

 tine in the lumina had become coloured with the stain. 



Transverse sections of B close to the base showed all 

 lumina choked with paraffin, while the walls between were 

 deeply stained with the saffranine. 



In polarised light with crossed Nicols the appearance was 

 very striking, the crystalline paraffin showing out strongly. 

 Transverse sections, 2 cm. from the end, showed the large 

 vessels still filled with paraffin. In some places neigh- 

 bouring vessels apparently quite filled with paraffin had 

 the intervening walls deeply stained ; at this level, however, 

 where the vessels were filled with paraffin the staining was 

 not quite so dark as elsewhere, though the colour was still 

 strong. The paraffin finally attained a height of 12 cm. in 

 one or two vessels. In no case was there any visible appear- 

 ance of shrinkage of the paraffin from the wall, although 

 in some sections, as might be expected, the action of the 



D 



