TRANSACTIONS OP SUB-SECTION K. 597 



and at temperatures below 12° to 15° C, growth is extremely slow. It can fer- 

 ment dextrose and lsevulose, producing alcohol and an evolution of gas which 

 consists of about 95 per cent, carbon dioxide and 5 per cent, hydrogen. A 

 characteristic acid odour resembling that of decaying lemons is also formed in 

 dextrose solutions. The acidity of the solution is somewhat increased, but the 

 presence of any of the commoner organic acids has not been recognised. Neither 

 saccharose, maltose, nor lactose appear to be attacked by it. It grows best in 

 neutral or very slightly acid media. Solutions containing more than 0-5 per 

 cent, malic acid are unfavourable to its development. It can ferment beer wort, 

 but the characteristic aroma aud flavour of sickness are not produced. Growth 

 is slight on all the solid media tested. Gelatine is not liquefied by it. 



The most promising measures for combating the disorder are sterilisation of 

 all vessels and appliances which have been contaminated with sick cider, storage 

 at a low temperature, and suitable blending of ciders to raise the acidity above 

 05 per cent, malic acid and to give a moderately rapid normal rate of fermenta- 

 tion. It has also been observed that ciders liable to the disorder will escape if 

 bottled very enrly in the season, whereas if bottled at the usual period they 

 quickly turn sick. 



2. A Method of determining the Baking Strength of Single Ears of Wheat. 

 By H. W. Harvey, B.A., and T. B. Wood, M.A. 



The advance of plant-breeding on Mendelian lines has created a demand for 

 methods of discrimination between individual plants, and this is especially the 

 case with wheats. The authors have met with some success in the use of the 

 following method for picking out ' strong ' wheats, and take this opportunity of 

 commending it to others who may be working on similar lines. 



It has been shown that the physical characters of. the gluten of any given 

 wheat depend on the acidity and the salt content of the cell sap. 1 The authors 

 have since found that while certain concentrations of acid and salt cause the 

 gluten to become coherent, a certain proportion of the protein is at the same 

 time dissolved. The solution of this protein possesses the ordinary characters 

 of a colloid solution. It is difficult to filter, rather viscous, and opalescent. In 

 experimenting with water-extracts of various wheats, the authors noticed great 

 differences in these characters, especially in opalescence. The difference in 

 respect of the latter property is greatly increased on addition of iodine, which 

 combines with the dissolved protein and forms a turbidity which has little ten- 

 dency to settle. Working on these lines, they have devised a method which 

 makes it possible to differentiate between flours with samples of about one 

 gram. The method is as follows : 1 gram of the sample is shaken with 20 c.c. 

 of cold water for one hour and then filtered. To 10 c.c. of the more or less 

 opalescent solution, 1 c.c. of 0-1 per cent, solution of iodine in potassium iodide 

 is added. After standing for one hour, the turbid solution is poured into a nar- 

 row tube with a plane-glass bottom. A very small electric lamp is placed 

 vertically under the tube. A plunger made of narrow tube with a plane-glass 

 bottom is screwed downwards by means of a rack and pinion into a turbid 

 liquid until the filament of the lamp just becomes visible. The depth of the 

 liquid is then read off on a scale. Working on these lines, the filament can be 

 seen through the following depths : — 



cm. 



Fife 3-4 



Karachi 6-8 



Square Heads' Master . . . 10-12 

 Rivett 15-18 



In all these cases the turbidity goes in the same order as the shape of the loaf. 



The method lends itself well to the testing of single ears. The grain from 

 an ear is rubbed out and ground in a small mill. One gram of the metal is 

 weighed out and treated as described above for flour. 



The authors have already succeeded in this way in picking out 'strong' and 



1 T. B. Wood, J. of Agr. 8c, vol. 2, pp. 139 and 207. 



