SECTIONAL TRANSACTIONS.—J, K. 443 
of America, contains a full account of the Ladd-Franklin theory of colour 
vision. Dr. Ladd-Franklin’s colour charts are to be issued by Stoelting & Co., 
Chicago. Ort (ef ae ba 
The light-sensations are (in the order of development) :— 
(a) White (including a dull white or ‘ grey’); 
(b) Yellow and blue added, but the yellow-blues revert to white; 
(c) Red and green added, but the red-greens revert to the yellow out of 
which they were developed. 
This is the great fundamental fact of colour-sensation. The two apparently 
incompatible facts, namely, chromatic sensations made up from three (Young- 
Helmholtz) or from four (Hering), become reconcilable according to the Ladd- 
Franklin development theory. 
25. Discussion on Colowr Vision. 
SECTION K.—BOTANY. 
(For references to the publication elsewhere of communications entered in the 
following list of transactions, see page 469.) 
Thursday, August 7. 
1. Discussion on The Ascent of Sap and Transport of Food 
Materials in Trees. 
(a) Prof. H. H. Drxon, F.R.S. 
Recent observations confirmatory of the cohesion theory of the ascent of sap. 
Renner’s and Ursprung’s measurements of the tensile strength of water. Holle’s 
and Bode’s demonstration of continuous water-columns in intact wilting plants. 
Bode’s direct observations of the effects of tension in transpiring shoots. 
Functions assigned to living cells in raising the sap. Ursprung’s views. 
Actions of cells of leaves. Transpiration of dead leaves temporary. Secretion 
of water by cells. Energy supply. 
Cohesion theory and transport. Carbohydrates, proteins, and enzymes in 
the transpiration-stream. Ringing. Changes in wood-parenchyma and trachee. 
Action of callus. Wood conveys organic substances upwards. Downward trans- 
port. Unsuitability of bast. Necessary velocity. Reversed current in wood. 
Transference of stimuli. Connections of growing and producing parts with 
storage organs. Introduction of organic substances into trachee. Local 
permeability-differences. Tension determines mass-movement of contents of 
trachee from any source to any sink. Function of bast and parenchyma. 
Association of bast and wood. 
(b) Dr. O. F. Curtis.—The Transport of Foods and Nutrients 
in Woody Plants. 
When ringing experiments were performed during the growing season, it 
was found that materials necessary for growth would not move up through 
the xylem past the ring. Analyses and cryoscopic determinations indicated 
that the movement of sugars and other solutes was interfered with by the ring. 
When, just previous to spring growth, rings were made at different distances 
from the tip, it was found that the growth above the rings was, roughly, pro- 
portional to the amount of food stored above the ring, and quantitative tests 
indicated that the upward transfer of carbohydrates had been interfered with. 
Other experiments showed that carbohydrates failed to move out of or into the 
xylem of a given region if this region were isolated, by rings through the 
phloem, from other tissues which would normally receive or supply these 
carbohydrates. 
It was further found that the normal upward movement of nitrogen and 
ash constituents was interfered with when the phloem was cut, though the move- 
ment was not completely stopped. This occurred whether the ring was made 
in the early spring before new xylem and leaves were formed, or in mid-summer 
