the Transpiration- Current. 409 
possible under water, and put standing for twenty minutes in 
water at 50° C., immersed to a depth of about 20 cms. We 
call these A, B, C, D. 
A is preserved in water at 5 °°- 
B is transferred to melted paraffin at 50° (melting-point 48°). 
C „ ,, gelatine coloured with Indian ink at 50°. 
D „ „ „ „ „ haematoxylin at 
5 °°- 
Each being immersed to a depth of 20 cm. and placed in 
bright light, the air temperature being j 6°. At the expiration 
of forty minutes all were transferred to water at 13°, when the 
end of each was thinly pared, and at 5.30 p.m. all were left 
finally standing in water at 13 0 . At 6.30 all were still fresh. 
At 11 a.m. on the 10th, i.e. after i5i hours, 
A Was still quite fresh. 
B „ very much flagged. 
C „ less flagged than B. 
D „ „ „ „ B, but more flagged than C. 
All were now transferred to a strong solution of saffranine, 
and put in full sunshine for i| 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 gelatine in the 
lumina had become stained with the saffranine. 
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 polarized light with crossed nicols the appearance was 
very striking, the crystalline paraffin showing out strongly. 
Transverse sections, 2 cms. from the end, showed the large 
vessels still filled with paraffin. In some places neighbouring 
vessels apparently quite filled with paraffin had the intervening 
walls deeply stained ; at this level, however, where the vessels 
were filled with paraffin the wall-staining was not quite so dark 
