i84 



Journal of Agricultural Research 



Vol. XII. No. 4 



During the three months' growth of the plants 1.40 gm. of potassium 

 nitrate were added. At the end of the period the dry weight of the 

 plant supplied with nitrate was nearly 60 times greater than that of the 

 plant where no nitrate was added. The relation between the growth of 

 nonleguminous plants and the amount of nitrate nitrogen supplied is 

 shown in a very striking manner in the following table taken from Hell- 

 riegel and Wilfarth {21, p. 53-54)'. 



Nitrogen as Ca (N03)2 added to pots, 

 gm 



Dry weight of oats (grain and straw) . 

 gin. . 



None 



0.3605 

 .4191 



0.056 



5.9024 



5-8510 

 5- 2867 



10. 9814 

 10. 9413 



21. 273a 

 21.4409 



o-33<5 



But little work has been done on the direct influence of nitrates on the 

 development of the Eumycetes. Some investigations have been made as 

 to the ability of certain fungi to assimilate nitrate nitrogen directly. 

 Ritter {42) studied many species and found that some forms would 

 assimilate nitrate directly, while others reduced it to nitrite and am- 

 monia. He found some forms which failed to grow on media containing 

 nitrate. Kossowicz {28) found that various fungi utilized nitrates and 

 that nitrite and ammonia were produced. 



Miinter {36) studied the influence of inorganic salts on the growth of 

 various Actinomycetes. He found that potassium and sodium nitrates 

 in quantities equivalent to 5 per cent permitted good growth of the 

 organisms but retarded spore formation. Calcium, barium, and stron- 

 tium nitrates in small quantities affected some species but not others. 

 Small quantities of these nitrates did not affect growth to any extent, 

 but larger quantities were detrimental to growth and spore formation. 

 Silver nitrate in all amounts studied almost entirely prohibited growth. 



Nitrates appear to exert some influence on the yeasts. Drabble and 

 Scott {13) studied the effect of sodium nitrate on these organisms. They 

 found that the greatest reproduction took place in solutions containing 

 0.2 gram-molecule of the nitrate. Increasing amounts of the salt led 

 to a decrease in reproductive activity until with 0.7 gram-molecule 

 present no reproduction took place. From their results it is evident 

 that small quantities of nitrate stimulated reproduction, whereas larger 

 amounts proved detrimental. Kayser (27) studied the effect of man- 

 ganese nitrate on yeasts. He found that the amount which produced 

 the maximum increase in the alcoholic fermentation of sugar varied with 

 the strain of yeast employed. He likewise found that manganese nitrate 

 produced greater increase than did the same quantity of potassium ni- 

 trate. Fembach and Lanzenberg {14) concluded that nitrates hindered 

 the rapidity of cell multiplication of yeasts but greatly accelerated the 

 action of the zymase. More alcohol was formed in the presence than in 

 the absence of nitrate. According to Kossowicz {28), nitrates are not a 

 suitable source of nitrogen for yeasts. 



