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crosses, however, were made without any special object, although perhaps in some
cases with the hope of getting a practically useful result from some of them.
Crossing was at that time generally considered as a way of stimulating or produ*
cing a variation. It was not until after the discovery of the Mendelian laws of
segregation that artificial crossTertilization became used systematically with a defi»
nite purpose and to a great extent. The honour of having applied these laws
in the practical breeding work is due to NilssonÆhle, who at once understood
the value of this discovery when improving both oats and winter wheat especi»
ally. It is easy to understand that the winter wheat in this case was especially
easy to work with. It now became the chief aim of the workers to combine the
high yield of Squarehead wheat with the hardiness of the old native land sorts
to a greater extent than they had hitherto been able to do by line selection.
When improving barley and oats, on the contrary, there have been no such
decisive characters of yield to work with. There have been no foreign sorts of
barley and oats either, which have been as superior to the old Swedish sorts as
Squarehead to old Swedish land wheat. At the beginning nobody hoped, not
even Nilsson*Ehle himself, that the yielding power of the former and the hardi*
ness of the latter could be combined to so great an extent as has now been done
by him.
The purpose of Crossing sorts with characters of different degrees of value,
for practical use, is to produce new combinations of characters which from a practical
point of view are still more valuable. Cross*breeding is a combinatiombreeding.
The way of working and the results already gained are clearly shown in the
following scheme, borrowed from Nilsson=Ehle. The numbers in parenthesis
give the average yield of the trials made at the Association at Svalöf. These are
expressed in relative numbers compared with Svenskt Sammetsvete (Swedish
Velvet Wheat) = 100. One of the sorts has no name and is therefore called
by its stock book number 0516; a stock book number is in reality a substitu*
tion for a name and is used in all tables, genealogical schemes, field books etc.
were the sorts are mentioned.
SUMMARY OF PART OF THE CONTINUED COMBINATION WORK WITH WINTER WHEAT AT SVALÖF.
Skåne Land Wheat (102) English Squarehead Wheat (99)
0516 (121)
Cone Wheat (128) X “£,) X
Poodle Wheat X
Sun Wheat (131) X .............J - Extra Squareh. Wheat II (129) X Small Wheat (131)
Sun Wheat II X Iron Wheat (140) X.,..- Fylgia Wheat (135) X (Sun Wheat II) XX Sw’^eyt’Ivet
Swedish Velvet
Wheat (100)
Fi 1915
Fs 1915
Fi 1915
Fi 1915
F2 1915
To describe the different characters of the crossed sorts more closely and
the purpose of each cross would take too long time. Iron Wheat, for instance,
has inherited gopd winterdiardiness and a high degree of resistance against yellow
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