8 HISTORICAL INTRODUCTION 



of Aspergillus niger was given by Steinberg in 1937, while in the 

 following year the same worker added gallium to the list of 

 elements essential for this fungus. 



While the mineral nutrition of no other fungus has received 

 so much attention as that of Aspergillus niger, sufficient in- 

 formation has now accumulated to justify the conclusion that 

 for the fungi in general a supply of trace elements is necessary. 

 Thus McHargue and Calfee (1931) concluded that zinc, man- 

 ganese and copper are necessary for the growth of A . flavus and 

 Rhizopus nigricans, and the same three elements were con- 

 sidered necessary for Ceratostomella Ulmi by Ledeboer (1934), 

 for Trichophyton interdigitale by Mosher, Saunders, Kingery and 

 Williams (1936), and for Phymatotrichum omnirorum by Rogers 

 (1938). Foster and Waksman (1939) reported that Rhizopus 

 nigricans fails to produce zygospores in absence of zinc, while the 

 favourable effect on development produced by zinc and copper 

 on a number of fungi belonging to different families has been 

 reported by Metz (1930) and for a number of species of Asper- 

 gillus by Roberg (1928, 1931). 



Thus, as far as our information goes at present, both higher 

 plants and fungi, or some of them, require a supply of man- 

 ganese, zinc, copper and molybdenum. Many higher plants have 

 been shown to need boron, and it is rather surprising that this 

 element, one of the most definitely established micro -nutrients 

 of higher plants, has received scarcely any attention from 

 workers on fungus nutrition. On the other hand, the need for 

 columbium and tungsten has so far not been claimed for any 

 higher plant. 



Very little information is available about the need for trace 

 elements of plants other than angiosperms and fungi, although 

 a few observations dealing with algae are on record. Thus man- 

 ganese has been shown to be essential for the unicellular green 

 alga Chlorella by Hopkins (1930, 1934) and for the diatom 

 Ditylum brightwelli by Harvey (1939). Roberg (1932) has 

 reported increased growth of two unicellular green algae 

 Coccomyxa simplex and Chlorella vulgaris as a result of small 

 additions of salts of iron, zinc and copper to the normal nutrient 

 solution. From his work, however, it is not made clear that 

 zinc and copper are actually essential for the growth of these 



