POTATOS: EXPERIMENTS IN CULTIVATION, ETC. 115 
cropping and cooking qualities, and in the hope of encouraging the 
raising of further immune varieties possessing good qualities for garden 
cultivation. Such well-known and widely grown varieties as ' Up-to- 
Date ' and all the forms similar to it, ' King Edward VII.,' and ' Arran 
Chief ' fall ready victims to the disease, so that when attempts are 
made to grow them in soil infected with the fungus the whole crop is 
often lost. On the other hand, a considerable number have been 
discovered by trial to resist the attack of the fungus completely. 
What produces immunity is unknown, but it is apparently due to some 
constitutional characteristic found in whole families of potatos, such 
as the ' Abundance ' type, seedlings of ' Great Scot,' and the like and 
probably breeding from these varieties would lead to the production 
of even higher yielding varieties than at present exist. While many 
of those grown showed excellent cropping powers, none seems quite 
equal to the ' Up-to-Date ' group in its power of yielding heavy crops. 
All the varieties mentioned below were grown, as the Table shows, 
from either Scotch or Irish seed, and the source of error in comparison 
between jdelds introduced by the use of English seed in competition 
with Scotch or Irish does not exist in this trial. It is, however, to be 
noted that seed from different parts of Scotland seems to vary in its 
cropping powers. 
Forty tubers of each variety were planted in April in well dug, 
lightly manured soil, in rows 2 feet 6 inches apart and 18 inches apart 
in the rows. Several varieties had their growth checked about the 
beginning of August by an attack of Phytophthora, and none proved 
entirely immune, but hone, with the exception of the earliest, showed 
much disease in the tubers, either at lifting time or subsequently. The 
varieties with coloured skins to the tubers appeared to be most resistant 
to the attack of Phytophthora in the foliage. 
The importance of the elimination of " rogues " from resistant 
varieties scarcely needs comment, but is not always easy. Perhaps 
the greatest difficulty exists in keeping separate the many closely 
related forms of one type, such as those capable of being grouped 
round ' Abundance,' and this does not perhaps greatly matter, since 
all are apparently resistant. ' Great Scot,' however, a resistant 
variety, is not easily distinguished either in the tuber 01 in the growing 
plant from ' Arran Chief,' a variety that succumbs to the disease. 
There are characters by which those constantly dealing with the 
plants may be able to distinguish them from one another, but these 
characters are mainly comparative, and not always distinct. The 
most reliable seems to be the colour of the young shoot as it first 
appears, for that of ' Great Scot ' is quite without purple tinge, while 
that of ' Arran Chief ' is always purple. This difference is not always 
apparent in the older stems, for in these in both varieties the skin 
is often more or less tinged with purple. 
The Vegetable Committee examined the Trials on two occasions, 
and as a result of their recommendations the awards shown in the 
following Table were made. The cooking qualities of some of the 
