16 BULLETIN 1471, U. S. DEPARTMENT OF AGRICULTURE 
damaged seed has been divided into three groups, and damage 
caused by storage conditions has been divided into four groups. 
Type A, field-damaged kernels, are those kernels having a slight 
to medium blister or scab. Damage has not progressed to an extent 
that the seed has swollen. T}^pe B, field damage, shows badly 
swollen seed, heavily blistered or scabby, that would not pass 
through a one-sixteenth by five-sixteenth-inch wire screen. Type 
C, field damage represents the green to brown immature kernels, 
resulting from drought or frost. These kernels are popularly called 
" flywings." Type D, storage damaged, represents seed damaged by 
external heat, that is, fire. In this type of kernel the seed coat is 
uniformly charred. Damage caused by heat of fermentation in 
storage is represented in Type E. Type F, storage damage, rep- 
resents the darkest kernels of this type of fire damage. The seeds 
when in this condition are dark brown or black. Later it is shown 
that in this type of seed not only the quantity of oil but the quality 
is changed. Type G represents water-damaged seed — that is, dam- 
age resulting from wetting during storage. 
A study of Table 11 shows that a damaged condition of a sample 
does not necessarily mean a reduction in the percentage of oil as 
compared to a sample free from damage. In fact, with kernels of 
type A, in a great many instances, there was a decidedly greater 
percentage of oil in the damaged seed than in the sound kernels. 
But kernels of this type do not invariably contain more oil than 
sound seeds. Numerous instances were found where the sound seed 
contained more oil than the damaged seeds. The reason why dam- 
aged seed may contain more oil than sound seed can not be stated 
fully. Field-damaged seed is the result of numerous factors — water, 
heat, air, and bacteria or fungi. If the temperature and moisture 
are favorable and the oxygen supply is good, rapid respiration and 
oxidation take place, the reserve materials — carbohydrates — are 
used up resulting in a loss in weight of the kernel. Inasmuch as the 
starches and sugars are dissipated more rapidly than the oil, because 
of the loss in kernel weight there is an apparent increase in the oil 
content. If the conditions are such that sprouting occurs, losses of 
both oil and earbol^drates take place which result in a reduction 
of the oil content. 
OIL CONTENT OF FOREIGN SEEDS FOUND IN FLAXSEED AND THEIR INFLUENCE 
UPON OIL CONTENT OF CAR LOTS OF FLAXSEED 
Flaxseed on the average contains more foreign material than any 
other grain crop coming to market. The average percentage of 
dockage found in flaxseed for the crop year 1924 for the State of 
North Dakota was 17.4 per cent, for South Dakota 15.6 per cent, 
and for Minnesota 13.8 per cent. 
An analysis of the foreign material shows it to contain, in addition 
to varying quantities of chaff, sticks, dirt, etc., weed seeds of such 
plants as lamb's-quarters, pigweed, green and yellow foxtail, millet. 
Russian thistle, wild buckwheat, flat and round-seeded false flax, 
Indian mustard, hare's ear mustard, tubling mustard, ball and black 
mustard, barnyard grass, smartweed, cockle, dock, wild oats, and 
wheat. 
