144 TRACE ELEMENTS IN ANIMALS 



to perosis was soon confirmed by Gallup and Norris (1937) and 

 several other groups of workers. Thus Heller and Penquite 

 (1937) found that addition of an aqueous extract of rice bran 

 or of traces of manganese to perosis-induoing diet practically 

 prevents the occurrence of the disease. Insko, Lyons and 

 Martin (1938 a) also showed that manganese exercised a protec- 

 tive action against perosis, whereas no such action resulted with 

 aluminium or zinc, but rather the reverse. The same workers 

 found (19386) that a minimum quantity of 30 p.p.m. of man- 

 ganese as manganese sulphate had to be added to an all -mash 

 basal ration containing 6 or 7 p.p.m. of manganese, if growth was 

 to be normal and perosis prevented. Amounts of manganese up 

 to 646 p.p.m. were not toxic. With low contents of manganese 

 they found that up to about 30 p.p.m. of manganese the degree 

 of bowing of the legs of their experimental chicks was inversely 

 proportional to the manganese content of the diet. 



Wiese, Elvehjem and Hart (1938) also found both rice bran 

 (15 per cent of the ration) and 0-0025 or 0-005 per cent of man- 

 ganese as manganese sulphate gave protection against perosis. 

 They found, however, that autoclaving the rice bran removed its 

 protective property, from which they concluded that some ther- 

 molabile substance must be involved, perhaps in association with 

 manganese, in preventing perosis. This finding would suggest 

 then that perosis may not be an outcome of simple manganese 

 deficiency, but that some other substance is involved as well. 



Gallup and Norris (1938) also showed that a large proportion 

 of the chicks hatched from eggs with a low manganese content 

 have short leg bones, and Lyons and Insko (1937) showed that 

 the embryos which were produced in eggs of hens fed on a 

 manganese-deficient diet were characterized by abnormally 

 short and thick legs and short wings. They found the deformities 

 could be prevented either by adding manganese to the diet of 

 the hen or by injecting manganese into the egg before incubation. 



Caskey and Norris (1939) found that excess of calcium and 

 phosphorus in the diet greatly reduced the availability of man- 

 ganese, and they found that 15-5 mg. of manganese supplied 

 orally over a period of 6 weeks with diets containing 1 per cent 

 of calcium and 0-5 per cent of phosphorus was as effective in 

 reducing perosis as 142 mg. of manganese supplied with 3 'per 



