Apr. 1894.] BOTANICAL SOCIETY OF EDINBURGH, 201 



A glance at the preceding Table shows that there is not 

 much difference in the results obtained in the two tubes, 

 when the whole apparatus is kept in the dark. In the 

 case of " Oxygen utilised," the differences are pretty equally 

 distributed in favour of either tube ; but in the case of 

 " Carbonic Anhydride produced " there appears to be a 

 slight increase in favour of the covered tube in each 

 experiment. These results may be more clearly seen by 

 collecting the totals as before : — 



Total Oxygen utilised. Excess in favour of 



Experiment. Clear Tube. Covered Tube. Clear Tube. Covered Tube. 



1. 23-87 c.c. 23-48 cc. 0-39 c.c. 



2. 20-38 „ 20-87 ,, ... 0-49 c.c. 



3. 28-57 ,, 28-48 „ 0-09 „ 



Totals, 7-2-82 c.c. 72-83 c.c. ... 0-01 c.c 



Totals, 67-57 c.c. 6810 c.c. 0-53 c.c. 



The total quantity of oxygen utilised by the seeds in the 

 three experiments is nearly identical in both tubes. The 

 totals of carbonic anhydride produced show a small increase 

 of 0'53 c.c. in favour of the covered tube, equal to 0'78 

 per cent, ou the mean of the total quantity of carbonic 

 anhydride formed. There is hardly any doubt that this 

 increase would be considerably lowered if the mean of a 

 larger number of experiments were taken. 



Considering these results as a sufficient test of the 

 efficiency of the apparatus, I may now give, in a tabular 

 form, the results obtained when strong diffused light was 

 admitted to the clear tube. 



