Cambridge Lniversity Agricultural Department. 115 
A fact was demonstrated which may prove to be the starting 
point of a rational method of combating plant diseases. In 
the course of the experiment a wheat, useless in many respects, 
but highly resistant to the attacks of yellow rust, was dis- 
covered. This was crossed with a susceptible variety. The 
three cultures shown were descended from the cross-bred so 
obtained ; they were grown under precisely the same condi- 
tions. One was entirely free from rust, whilst its neighbour 
was smothered, and the third culture consisted of rust-free 
and rust-covered plants grown from the same ear of wheat. 
The rust-free form breeds true to this characteristic. 
The second section of the exhibit dealt with the 
composition of mangels. During the past few years, a very 
large number of analyses have been made by the Department. 
It has been shown that the ordinary mangels of commerce 
resolve themselves into five well-marked types, viz., the 
Yellow Globe, with white flesh ; the Yellow Intermediate, with 
white flesh ; the Golden Globe, with yellow flesh ; the Golden 
Tankard, with yellow flesh ; and the Long Red, with pink 
flesh. Some other types, such as Red Intermediates, are 
occasionally met with, but are much less common than the 
foregoing. Strains of these different types of mangels are 
sold under many names; but, so far as the composition is 
concerned, the different strains are identical. This was shown 
by means of a diagram. 
Although the different seedsmen’s strains of any one type 
of mangel have the same composition, they may differ both in 
form and productiveness, according to the care with which 
the seed has been grown. The points to which seedsmen have 
given attention are shape and cropping quality, and these are 
the points in which the best strains of seed excel inferior sorts. 
The average composition and the total yield of dry matter 
and sugar of the five different types of mangel mentioned 
above were also shown by diagrams. On the average of all 
the analyses, Golden Globe was shown to be richest in dry 
matter and sugar, containing 12‘4 per cent, of the former, and 
8'2 per cent, of the latter ; but this sort is so closely followed 
by the Long Red and Golden Tankard types that the three 
may be classed as equal. The Yellow Globe, with an average 
of 10 - 7 per cent, of dry matter, is distinctly the poorest in 
quality. Of the five types, Yellow Globe and Long Red are 
about equally good croppers. When both quality and quantity 
are taken into account, the first place is occupied by the Long 
Red mangel. This, on the average, produced 3*9 tons of dry 
matter, and 2*9 tons of sugar per acre. Golden Globe is rather 
an inferior cropper, but with its high quality it takes second 
place and produced 3*3 tons of dry matter and 2'3 tons of 
I 2 
