BUREAU OF CHEMISTRY. 587 



PLANT PUYSIOLOGICAL CHEMISTRY. 



The work of the Laboratory of Plant Physiological Chemistry has 

 been continued along practically the same lines as in former years. 

 Besides the extensive collaborations with the various offices of the 

 Bureau of Plant Industry, an extensive investigation of the methods 

 of baking bread and of the conditions of the bake shops of the large 

 cities in this country has been begun. An investigation has also 

 been undertaken of the use of coloring matter in macaroni and the 

 ditl'erences between macaronis made from different classes of flour. 



Over 1,200 samples have been received in this laboratory during 

 the past 3'ear, GOO being cereals, 300 flours, 40 macaronis, 1"20 other 

 cereal products, 50 of foliage, 60 of beet roots, practically 100 of alka- 

 line extracts, and over 100 miscellaneous samples, such as soy beans, 

 hay, blueberry stems, etc. The work on these samples has necessi- 

 tated the making of about 15.000 determinations. 



Bulletin 138 gives the results of a study of the changes in compo- 

 sition which the wheat seed undergoes during the first two or three 

 weeks of germination and growth, while Bulletin 149 gives the 

 results of growing wheat seedlings in solutions of various degrees of 

 acidity and alkalinity. This latter bulletin has a practical agricul- 

 tural value in explaining why soils treated with ammonium sulphate, 

 potassium chlorid, potassium sulphate, and similar substances be- 

 come acid and refuse to remain productive unless a sufficient amount 

 of lime is added to neutralize the acidity. 



Much work has been done on methods of determining the amounts 

 of cholin in ordinary flour and in cottonseed flour. This work may 

 be useful later to show why cottonseed has been regarded as poison- 

 ous to young cattle and hogs. 



Other subjects investigated have included starch and starch prod- 

 ucts, potato drying, graham flour, and canning tomatoes. 



ANIMAL PHYSIOLOGICAL CHEMISTRY. 



The work of this laboratory during the past fiscal j^ear has greatly 

 increased over that of the preceding year. There were G69 samples 

 examined, as follows: One hundred and fifty-six of eggs, 396 per- 

 taining to the infant food and cottonseed bread studies, 56 of fish, 

 including canned salmon, sardines, and shad, 11 of meat extracts 

 and i)()uill()n cubes, 28 of gelatin, and 22 of a miscellaneous charac- 

 ter, including work to determine evidence that potato chips had been 

 peptonized, the analysis of so-called concentrated food preparations 

 containing meat and chocolate, and the examination of oysters for 

 evidence of decomposition. 



The work on the analysis and study of the different brands of 

 infant foods is noaring completion. A number of charts, which 

 were made showing the composition of the different foods prepared 

 according to the directions accompanying each, have been in demand 

 throughout the country in connection with exhibitions on the care of 

 infants and infant feeding. 



The work on deterioration and decomposition of foods was de- 

 voted largely to studies on eggs. Assistance was rendered in the 

 investigation conducted at Omaha, Nebr., last year and during this 



