June 2,1923 
Effect of Manganese on Plant Growth 
793 
be taken in the preparation of a manganese-free medium in which to 
grow plants. 
(4) Manganese is intimately associated with compounds of iron, phos¬ 
phorus, and calcium, and since very small amounts of this element are 
required for the growth of plants it is quite probable that the contami¬ 
nation of plant nutrients with manganese has hitherto been an unrec¬ 
ognized source of error in determining the necessity of this element in 
plant economy. 
(5) Apparently leguminous plants are more sensitive to the lack of 
manganese than are the nonlegumes; however, further data obtained 
by growing nonleguminous plants for more than one generation in a 
manganese-free medium may be necessary to prove this point. 
(6) A very small amount of manganese is required for the normal 
growth of plants. 
(7) Seeds of the plants tested (radish, soybean, cowpea, field pea, 
and corn) do not contain enough manganese for the growth of the plant 
to maturity. 
(8) The seeds of some plants contain enough manganese to maintain 
a normal development for the first four or six weeks of their growth; there¬ 
fore experiments conducted for a shorter time in a manganese-free medium 
are not likely to give any indications as to the necessity of this element 
in the growth of plants. 
(9) The lack of manganese affects the production of the dry matter 
in plants, thus indicating that it has some very important function in 
carbon assimilation. 
(10) The etiolated condition of the young and tender leaves and buds 
obtained in well-controlled experiments indicates that manganese has 
a function in the photosynthetic process and the formation of chlorophyll. 
(11) Manganese apparently is essential for the normal growth and 
development of plants. 
(12) Further investigations on this subject are under way in which 
an attempt will be made to show the relation of manganese to other 
important phases of plant and animal life. 
UTKRATURB CITED 
(1) B]0 rtrand, Gabriel. 
1897. SUR r ’intervention DU manganese dans EES OXYDATIONS PROVOQU^ES 
PAR EA EACCASE. In Compt. Rend. Acad. Sci. [Paris], t. 124, p. 
1032-35- 
(2) BrencheEy, Winifred E. 
1914. INORGANIC PEANT POISONS AND STIMUEANTS. ix, 110 p., 19 fig. Cam¬ 
bridge. Bibliography, p. 97-106. 
(3) Eweee, E. E. 
1902. OCCURRENCE AND IMPORTANCE OP SOEUBEE MANGANESE SAETS IN SOIES. 
In Science, n. s., v. 16, p. 291. 
(4) Funchess, M. J. 
1919. ACID SOIES AND THE TOXICITY OP MANGANESE. In Soil Sci., V. 8, p. 69. 
(5) keeeey, w. p. 
1914. THE PUNCTION OP MANGANESE INPEANTS. In Bot. Gaz., V. 57, p. 213-227 . 
Literature cited, p. 226-227. 
(6) McHargue, J. S. 
1919. THE EPPECT OP manganese ON THE GROWTH OP WHEAT: A SOURCE OP 
MANGANESE POR agricueturae PURPOSES. In JouT. Indus. and 
Engin. Chem., v. ii, p. 332 - 335 * 4 %♦ 
(7) Oearu, M. D. a. 
1920. CONTRIBUTION A e’ETUDE DU ROEE DU MANGANESE EN AGRICUETURE ET 
SON INPEUENCE SUR QUEEQUES MICROBES DU SOE. Bul. L’Univ. 
Bucharest, ser. A, no. 850, 122 p. 
