[Vol. 10 



322 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



dry wt. 

 10 days ; the ratio NW was consequently greatest in this period 



and decreased as the culture aged. This diminution of the ratio 



dry wt. 



-777 — — was found to correspond to the peptone content of the 



medium ; the greater the initial growth the greater the ultimate 

 decrease in weight. Rise of temperature decreased this fraction. 

 Age and temperature determined also the economic coefficient 

 of the N-free complex of the peptone. Zinc salts had no effect 

 on the utilization of peptone, so that the increase in harvest 

 obtained with media containing carbohydrate as a C source to 

 which Zn had been added was explained as due to stimulation of 

 carbon metabolism. Citromyces behaved similarly to Aspergillus, 

 but produced a slightly higher percentage of NH,. 

 Boncquet ('16) found nitrites and NH, in material from 



a * *f 



mosaic" tobacco and potato, and from beets affected with 

 "curly leaf." He ascribed the presence of these unusual nitrog- 

 enous forms to the "reducing power of the internal bacterial 

 flora." Jodidi, Moulton, and Markley ('20) ran parallel nitrogen 

 analyses with normal and "mosaic" spinach and found remark- 

 able differences. Diseased plants had a smaller percentage of 

 total protein, nitrate, acid amide, mono- and di-amino N, but a 

 slightly higher percentage of NH, than normal plants; nitrites 

 were found only in the diseased plants. Obtaining similar results 

 with material from normal cabbage and that affected by the so- 

 called "mosaic disease "they believed they were warranted in cata- 

 loging the disease as "mosaic." Klotz ('21), using the same meth- 

 ods, obtained similar analytical data working with celery leaves 

 affected with the Cercospora blight ; later it was found that celery 

 leaves diseased with Septoria blight showed a similar chemical 

 picture. In the latter case more modern methods were used. 



Experimental 



MATERIALS AND METHODS 



Three fungi, viz., Aspergillus niger, Sphaeropsis malorum, and 

 Diplodia natalensis were used in the investigations reported in 

 this paper. Work with Phoma Betae, a form particularly in- 



