106 STUDIES OF PHOTO-SYNTHESIS 



placed loosely on top to protect from excessive light and heat, which 

 are fatal to algae. 



In order to save space in tabulation the amounts of nitrogen 

 found by the Kjeldahl determination carried out at the conclusion 

 of the experiments are here placed opposite the description of the 

 treatment of each jar: 



No. 1. Tap water and algae only, glass lid screwed down, kept 

 in light. Nitrogen =0-3 mgrm. 



No. 2. Tap water and algae only, no glass lid, top covered by 

 fine lawn, kept in light. Nitrogen=l-6 mgrms. 



No. 3. Tap water and algae only, the glass lid screwed down, 

 kept in darkness. Nitrogen =0-1 mgrm. 



No. 4. Tap water and algae only, covered by fine lawn, kept in 

 darkness. Nitrogen=O3 mgrm. 



No. 5. Tap water, algaa, 2 c.c. of 5 per cent. Na 2 HP0 4 ,12H 2 

 (i.e., 0-05 per cent, of Na 2 HP0 4 ,12H 2 0), lawn cover only, kept in 

 light. Nitrogen=8-l mgrms. 



No. 6. Tap water, algae, 0-05 per cent, of Na >> HP0 4 screwed- 

 down glass lid, kept in light. Nitrogen=l-0 mgrm. 



No. 7. Tap water, algae, 0-05 per cent, of Na.,HP0 4 , 0-05 per 

 cent, of NaN0 2 , lawn cover only, kept in light. Nitrogen = 

 12-3 mgrms. 



No. 8. Tap water, algae, 0-05 per cent, of Na a HP0 4 , 0-05 per 

 cent, of NaN0 2 , screwed-down glass lid, kept in light. Nitrogen= 

 0-7 mgrm. 



No. 9. Tap water, algae, 0-05 per cent. Na. 2 HP0 4 , 0-05 per cent. 

 NaN0 2 , formaldehyde vapour at high dilution supplied from side 

 tube as described below, glass lid screwed down, kept in light. 

 Nitrogen 3-8 mgrms. 



No. 10. Tap water, algae, 0-05 per cent. Na 9 HP0 4 , no NaNO.,, 

 formaldehyde vapour, glass lid screwed down, kept in light. Nitro- 

 gen =1-0 mgrm. 



No. 11. Tap water, algse, 0-05 per cent. Na 2 HP0 4 , 0-05 per cent. 

 NaN0 2 , dilute methylic alcohol vapour supplied from side tube, 

 glass lid screwed down, kept in light. Nitrogen=74 mgrms. 



No. 12. Tap water, algae, 0-05 per cent. Na 2 HP0 4 , no NaN0 2 , 

 dilute methylic alcohol vapour from side tube, glass lid screwed 

 down, kept in light. Nitrogen=l-l mgrms. 



Notes on Growth. These were taken at frequent intervals and 

 were con.coid.ant throughout ; so. as to, sa.ve space only two samples 



