4 BULLETIN 1146, U. S. DEPARTMENT OF AGRICULTURE. 
Pott (37) showed that the water content decreased, while the 
total nitrogen, starch, and crude fiber contents increased in the tubers 
as they matured. : 
Prunet (39) considered that during growth the nutritive sub- 
stances are uniformly distributed in the tuber, but after full size has 
been reached there is a movement of these substances toward the 
apical buds. 
Jones and White (24) in 1899 reported some experiments made on 
Delaware and White Star varieties of potatoes in Vermont. From 
analyses of tubers from both Bordeaux-sprayed and unsprayed plots, 
they concluded that the variations in yield were of more importance 
than variations in composition. The unsprayed tubers showed the 
presence of more water and ash than the sprayed tubers. As all of 
the tubers matured the solids and nitrogen-free extract decreased 
somewhat, while the ash, protein, and crude fiber increased slightly. 
Stewart, Eustace, and Sirrine (46) im 1902 reported that one lot 
of tubers from Bordeaux-sprayed plants gave higher solids and 
starch results than a corresponding lot from unsprayed vines. 
Woods (51) of the Maine station in 1919 published analyses show- 
ing that tubers from Bordeaux-sprayed potato vines averaged 19.1 
per cent starch and that:tubers in the same field from unsprayed vines 
averaged 17.5 per cent starch. The dry matter in the tubers from the 
sprayed portions of the field was also 14 per cent higher than that 
in the tubers from the unsprayed portions. 
PLANTS IN GENERAL. 
Sorauer (45) observed that swellings were formed on the leaves of 
potato plants by the action of copper salts. Sections of these 
growths showed that they were composed of parenchyma cells so 
strongly hypertrophied as to break the epidermis. 
Frank and Kriiger (79) in 1894 obtained a definite improvement in 
growth by treating potato plants with a 2 per cent Bordeaux spray. 
The effect of the copper was most marked on the leaves and was 
chiefly indicated by physiological activity rather than morphological 
changes. The leaves were thicker and stronger and their hfe was 
lengthened. The chlorophyll content was apparently increased and 
correlated with this was a rise in the assimilating capacity, more 
starch being formed. A rise in transpiration also occurred. <A sub- 
sidiary stimulation took place in the tubers, as the greater quantity 
of starch produced required space for its storage. The ratio of tuber 
formation on treated and untreated plants was 19:17 and 17:16. 
These investigators held that the action was catalytic, that is, an 
increase in photosynthesis resulted from the presence of copper. 
Rumm (40) in 1895 noted that grape foliage sprayed with Bor- 
deaux showed thickened leaves of a blue-green color which outlived 
the leaves of the unsprayed vines. After measuring leaves from 
sprayed and unsprayed vines Rumm presented data showing that the 
thickness of the leaf, the epidermis, the palisade tissue, and the 
parenchyma was increased in the case of the sprayed vines. These 
data suggest that copper was taken into the growing leaf where it 
produced certain morphological changes. 
Lodeman (32) found that the thickness of plum leaves and prune 
leaves was increased by the application of Bordeaux spray. 
