17 



process, but also enlarged tbe size of the fruit. Cugiui tries to explain 

 this on the ground of stimulation of the protoplasm and increased 

 production of chloroplasts in the epidermis. 



OUaANIC COMPOUNDS CONTAINING IRON. 



Haemoglobin is not the only organic iron compound in organisms. 

 Bunge isolated from the yolk of eggs a nuclein-like body, h^matogen, 

 which contained 5 per cent phosphorus and 0.23 per cent iron, and 

 similar substances were observed by Zaleski in the liver of animals 

 and by Macallum and Stoklasa in the nuclei of plant cells. Spitzer 

 found in animals oxidizing enzyms, which were nucleo-proteids con- 

 taining about 0.2 per cent of iron. 



IRON IN FUNGI. 



The question as to whether iron salts are necessary for fungi was 

 formerly answered in the negative. Molisch,i however, observed that 

 even very small traces of iron salts have a great effect upon the 

 growth of fungi, and having discovered traces of it in the ash of 

 various fungi, he considers it a necessary element for them. Indeed 

 slight traces of iron are frequently present in the nutrient compounds 

 used for the cultivation of fungi. Certain writers admit that iron pro- 

 daces a beneficial effect, but deny that it is absolutely necessary. 

 However, Molisch's observation that in fungi iron can not be replaced 

 by nickel, cobalt, manganese, or zinc deserves special consideration. 

 Traces of zinc and related salts will, according to Raulin, Ono, and 

 Richards, also increase the fungas mass in a given time. Richards 

 has shown that the nutrients are more economically disposed of under 

 this influence. It may also be mentioned here that Gautier and Drouin 

 observed that ferric oxid promotes the fixation of atmospheric nitrogen 

 by soil bacteria.^ 



MANGANESE IN PLANTS. 



Physiologically, manganese can not replace iron in plants. Plants 

 have also been raised to perfection in culture solutions which con- 

 tained no trace of manganese. However, the ash of plants, especially 

 of woody ones, sometimes contains even inore manganese than iron. 

 Schroeder calculated for 1 hectare of eighty year old beech trees near 

 Tharand a content of 104.1 kilos of Mn304, but only a content of 7.92 

 kilos of FcaOgl The ash of Pinus strohus showed a content of 2.06 per 

 cent Mn304, and that of Populus tremula 1.06 per cent Mn304 (Weber). 



In the case of pines, even the pollen grains contain manganese. 

 Ramann found in them 5.23 per cent ash, and in 100 parts of this ash 

 1.95 per cent ferric oxid and 1.12 per cent manganic oxid (Mn304).4 



' Sitzungsber. d. Wien Akad., 1892, Vol. GUI. Aso found nearly 5 per cent ferric 

 oxid in the ash of the spores of Aspergillus oryzce. 

 2Bot. Jahresber., 1888, p. 29. 

 ^Wolff's Aschen Analysen, Vol. II. 



^The manganese content in oxidizing enzyms has been mentioned on p. 9 

 7478— No. 18 2 



