242 MANURES FOR TREES 



manganese in the seeds and actively vital 

 parts of plants is confirmatory of its importance 

 in the vegetable economy. Among other functions 

 it appears to develop the odours of fruits, flowers, 

 leaves, etc. Lecomte discovered, in the various 

 parts of the vanilla plant, the presence of an 

 oxidising ferment, similar to the oxydases studied 

 by G. Bertrand. Manganese, which is regarded as 

 the vehicle of the oxygen, is present in all parts of 

 Vanilla planifolia ; and it is highly probable 

 that it plays an important part in the preparation 

 of vanillin and the odoriferous principles in the 

 conifers and other plants. 



Bertrand^ states that the activity of the 

 oxydases is proportional to the amount of man- 

 ganese present, since the absorption of oxygen in 

 the presence of manganese was found to be con- 

 siderably greater than when no manganese was 

 present ; and that manganese cannot be replaced 

 by other metals. Bertrand has suggested that the 

 oxydases may be special combinations of proteids 

 with manganese — the manganese being the 

 oxygen-carrier. 



Manganese is also present in the animal kingdom. 

 It was discovered, by the author, in the blood of 



1 Bertrand, Comptes Bendus, t. 120, p. 266 ; t. 124, p. 1032 ; and 

 Bulletin de la SocUti Chimique de Paris, 3s., t. 15, p. 793. 



