Intake Levels. Normal intake is about 4 mg/day for man and about 

 0.8 mg/day for rats. Dietary levels on a dry-matter basis approximate 

 50 ppm for sheep and cattle, 7 to 50 ppm for swine, and 50 ppm for 

 poultry. Animal tissues contain 0.2 to 4 ppm manganese. In rabbits as 

 much as 0.2 to 0.3 g daily for 3 weeks produced no toxic symptoms. A 

 recommended nutrient solution for plants contains about 0.11 ppm, and 

 crop plants have been found to have from 25 to 1000 ppm. 



Radioassay. No problems are presented by routine beta or gamma 

 counting. 



Chemistry. The general methods of Chap. 5 may be followed for dry- 

 or wet-ashing. Manganese is usually determined by oxidation to per- 

 manganate in acid solution with periodate or persulfate, followed by 

 colorimetric evaluation. These methods are not generally so sensitive 

 as desired for biochemical studies. A modified catalytic method has been 

 described which reciuires about 0.005 ^g manganese in the sample (Mn-1). 

 A microbiological method requiring 0.5 /xg/ml of test solution has been 

 reported (Mn-2). 



Typical Methods. In a study of pancreatic localization and secretion, 

 mice and rats were injected intravenously with 50 to 60 no, Mn*^, whereas 

 dogs received 333 to 541 ixc in 7 mg Mn as MnClo in saline (Mn-3). 

 Radiomeasurements were made with a gamma-ray ionization chamber. 

 Cyclotron-produced Mn^"* was used for distribution studies in rats and in 

 chicks on manganese-deficient diets (Mn-4, Mn-5). For counting, the 

 tissues were dry-ashed at 500°C, and carrier added to facilitate subsecjuent 

 precipitation of Mn02. Direct beta or gamma counting would eliminate 

 the necessity for the chemical operations and probably give comparable 

 results. The manganese metabolism of hornets has been studied using 

 cyclotron-produced radioactivity (Mn-6). In one experiment the 2.59-hr 

 Mn*^ was used, and in another, a mixture of Mn^- and Mn". The radio- 

 isotopes were incorporated into a honey solution upon which the insects 

 fed. Routine chemical analyses, Geiger counting, and contact auto- 

 radiography were employed. 



The uptake of Mn^^ was studied in flax, peas, cabbage, and tomato 



