8 



the fact that nitrification is at a standstill on the grass plots which 

 have become acid through the continued application of ammonium 

 salts, as described in the last report. The growth of grass still 

 continues on these plots, and the nitrogen it contains must have been 

 taken up as ammonia. The authors noticed certain differences in 

 the habit of the plants that were feeding on ammonia only — for 

 example, an increased percentage of nitrogen in the dry matter, a 

 darker colour of the leaf, and a dwarfer habit. Similar differences 

 may be seen in the habit of the wheat and barley plants growing on 

 the Rothamsted plots with ammonium salts and nitrate of soda 

 respectively ; much greater length of straw is always obtained with 

 nitrate of soda in our experiments. 



It would thus appear that even in the open field at Rothamsted 

 the ammonium salts are not wholly nitrified before they reach the 

 plant. 



• The development of the Grain of Wheat," by A. D. Hall and 

 W. E. Brenchley. This paper deals with the progressive changes 

 in the composition of the grain of wheat during its formation and 

 ripening, and represents the chemical side of the work, the botanical 

 aspect of which was described in the last report. A large number 

 of heads of wheat were marked on one day when they were just 

 putting out their first flowers, so that it could be assumed that they 

 were all of the same age, and at the same stage of development. 

 One hundred or more of these marked heads were then taken at 

 intervals of three days until the grain was fully ripe ; the grain 

 was extracted and analysed, and in one year the straw was also 

 analysed. 



On examination of the curves expressing the results the authors 

 distinguish three stages — the formation of the pericarp, the filling 

 of the endosperm, and the ripening process. The material forming 

 the pericarp contains a larger proportion of nitrogen in the dry 

 matter, and a smaller proportion of phosphoric acid in the ash, 

 than does the endosperm material. As soon as the endosperm 

 begins to fill, the plant moves into it material that is practically 

 uniform in composition at all stages, early and late in the 

 filling. There appears to be no justification for the opinion usually 

 held that the proteins are moved in first and the carbohydrates later. 

 The ripening process is in the main one of desiccation, although there 

 is some change from non-protein to protein. The authors incidentally 

 show that both the nutrition and assimilation of the plant continue to 

 a much later date than has been usually supposed. The total amount 

 of dry matter, nitrogen, and ash in the plant increases to within a 

 fortnight of harvest. The authors conclude that it would be safe to 



