1914] 
FOSTER—SOURCE OF COMBINED NITROGEN FOR ULVA 233 
COMPARATIVE TABLE SHOWING GROWTH OF STRIPS OF ULVA IN VARIOUS 
NITROGEN-CONTAINING SOLUTIONS 
Ammonium nitrate Urea Acetamid 
Growth Growth Growth 
Cone. | Sote] Sole | 09. Sol*| So.*| C9? [sa | Sol* 
A B А В А В 
Check 0.8, 0.3 Check 0.8| 0.3) Check 0.8 | 0.3 
0.00005 1.0| 0.5 0.0005 1.4| 0.5 0.001 0.8 | 0.4 
0.0001 1.4 1.5 0.001 1.6 0.6 0.005 Lo 0.4 
0.0005 9-20 0.005 1.6 1.4 0.01 0.7 0.5 
0.001 1.4 1.2 0.01 0.9 1.3 0.10 1.0 10 
Sodium asparaginate Acetanilid Dimethylanilin 
Growth Growth Growth 
Con. [Sol*|Bol* | Ce [ба | soe) 60064 (вое | вое 
А В А В А В 
Check 0.8 | 0.3 Check 0.8 | 0.3 Check 0.8 | 0.3 
0.002 0.7 | 0.6 0.0005 0.6 | 0.5 0.002 0.3 | 0.4 
0.01 0.9 | 0.2 0.0025 0.0 | 0.0 0.02 0.0 | 0.5 
0.05 0.7 | 0.0 0.0125 0.0 | 0.0 0.10 0.0 | 0.0 
* Sol. А = natural sea-water; sol. В = artificial sea-water. 
1 Conc. under dimethylanilin represents fractions of а saturated solution in dis- 
tilled water at 2090. 
Acetamid has а somewhat lower nutrient value than ammo- 
nium nitrate or urea, but still it causes a greater growth than 
do the control solutions to which no foreign nitrogen was added. 
The alga in acetamid solutions appeared normal in every way. 
The results with the sodium asparaginate were rather unex- 
pected. This compound is well known to be a good nutrient 
for many fungi and fresh-water alge. For Ulva, on the other 
hand, sodium asparaginate appears to have no appreciable 
nutrient value. In no case did it cause any notable increase 
in growth, although the algal material appeared perfectly normal. 
