90 



KNOWLEDGE. 



March, 1913. 



gramme). The last year's sample was particularly 

 plump and numbered twenty-two grains to the 

 gramme. (See Figures 80-85). 



Wheat of 1911 was a sample of Rivet Wheat 

 grown in Huntingdonshire of plump grains 

 which numbered twenty to the gramme. (See 

 Figures 86 and 87). 



On treating the whole grain flour (crushed in the 

 laboratory) with water, that from the Mummy 

 Wheat produced a thin paste without any strength 

 of dough whatever. The apparent stickiness and 

 lack of elasticity led the writer to believe that a 

 considerable amount of soluble dextrin and possibly 

 sugar would be found. This assumption proved to 

 be unfounded on analysis. 



The flours from the wheats of 1852, 1853 and 1854 

 showed plenty of elasticity on doughing with water, 

 and had not suffered apparentlv in " strength " through 

 deterioration of their gluten by long storage. 



The lack of a sufficiency of the sample of Mummy 

 Wheat prevented any investigation into the state of 

 its nitrogenous compounds, which, though still 

 present in considerable proportions, had completely 

 lost the physical characteristics of wheat gluten. 



Microscopical Examination. 



In a previous paper, by means of transparent 

 sections taken through the wheat berry, the writer 

 was able to show the changes and direction of change 

 taking place in the grain during germination. It 

 was hoped that sections of the wheats here under 

 examination, taken in a similar manner, would reveal 

 certain structural changes which might be expected 

 to have taken place during the passage of so many 

 years. Examination, however, shows that the actual 

 structure of the germ remains unchanged, and that 

 only the coalescence of the minute cells has resulted. 

 In the wheats of 1852, 1853, and 1854, the germ 

 remains unaltered in appearance. 



Closer examination of the endosperm of the 

 Mummy Wheat reveals the decomposition of the 

 cementing material which binds the bundles of 

 starch together, and, consequently, the extreme 

 friability of the wheat grains when crushed, and the 

 lack of adhesiveness of the resulting flour when 

 doughed, are accounted for. The actual starch grains 

 are not affected in any way, and it may be assumed, 

 therefore, that no diastase had penetrated into the 

 endosperm as would occur on incipient germination. 



As will be seen from the acidity figures of the 

 ground berries there is no great increase in sourness 

 in the w^heat grains up to fifty years, but a very pro- 

 nounced increase in the more ancient Mummy 

 Wheat. 



This fact is interesting in the light of Professor 

 Bell's experiments with stored flours, made in 1907, 

 and other experiments made in America in the two 

 following years. 



The general indication of these tests showed that 

 the increase of acidity was more pronounced in the 

 case of low-grade than high-grade flours, and was 

 due chiefly to the action of acid-producing bacteria 

 which have ready access to stored flour. 



It was further proved that dampness was the 

 prime factor which favoured the production of 

 acidity, whilst temperature was of little or no 

 account. 



In normally air-dried wheats, sufficient moisture 

 does not exist to produce acidity rapidly, and the 

 protective covering of the husk is thick enough to 

 stay for a considerable period the action of aerobic 

 acid-producing bacteria. 



As soon as the husk is capable of being penetrated 

 by air, either from the slow growth of moulds and 

 smaller fungi on the exterior of the grain or from 

 chemical oxidation, the growth of the acid-producing 

 bacteria within the berry is favoured. 



It is of further interest to note that increase of 

 acidity is accompanied by reduction of the gluten 

 strength, a fact which has been noted by Wood and 

 others who found that even N/1.000 solutions of 

 hydrochloric acid and varying dilutions of other 

 acids such as phosphoric, oxalic, acetic, lactic, citric 

 and tartaric, were capable of producing degradation 

 of the gluten and a corresponding reduction in the 

 " strength" of the dough. 



The most prominent feature of the microscopical 

 examination of the flours produced from the wheats 

 under discussion was the appearance of long, sharp- 

 pointed angular pieces, into which the oldest wheat 

 fell when crushed. (See Figure 88). 



The shape of the particles is entirely different 

 from those produced from normal wheat, or from 

 the wheats up to fifty years of age. (See Figure 89). 



This is accounted for by the decomposition of the 

 binding proteid matter and by the cleavage which 

 has taken place when the grain is crushed along the 

 lines of the proteid matter which binds the bundles 

 of starch granules, rather than along the non-proteid 

 divisions which separate the starch-proteid groupings. 



It is without doubt correct that in normally aged 

 and dried wheat the first cleavage is along the lines 

 of the parenchymatous cellulose, by means of which 

 the endosperm is divided up into groups of starch 

 granules embedded in gluten. These groups are, as 

 a rule, angular and also four-sided, and are readily 

 distinguishable from the sharp-pointed and tapering 

 pieces into which the endosperm breaks up when 

 the Mummy Wheat is crushed. 



(To be continued.) 



