618 Mr. F. Kidd. The Controlling Influence of 



content of similar seed during ordinary germination on damp sand after 

 complete air drying in the laboratory : — 



Table IX. — The C0 2 Content of Beans (Viciafaba) and Peas {Pimm 

 sativum) while germinating. 



Description of seed. 



Grammes of 



H,0 per 

 100 grm. of 

 seed. 



Cubic centi- 

 metres of 

 C0 2 per 



100 grm. of 

 seed. 



Ratio C0 2 /H 2 in 

 tissues of seed. 



• 



Peas after 18 hrs. germinating 



67 



64 



96/100 



None 



j) » 25 „ 



67 



41 



61/100 



None 



» >. 39 „ 



70 



43 



62/100 



Sprouting 



» » 64 „ 



70 



39 



55/100 





65 



16 



24/100 





Beans after 24 hrs. germinating 



58 



20 



34 -5/100 





Beans after 7 days in germina- 









ting conditions 







41/100 



3) 



Beans after 5 days without testas 











in germinating conditions ... 







16 -5/100 



>1 



The experiments lead to the conclusion that in the maturing seed, in the 

 case of beans and peas, the C0 2 content of the tissues is higher than that under 

 which actually germination takes place. In short, so far as these experi- 

 ments have gone, it would seem that where the C0 2 content of the tissues is 

 above a certain point germination does not occur and that the CO2 content 

 must fall below this point before germination takes place. 



Section IV. — Contrast of Depressant Action of High Partial Pressures of 

 Carbon Dioxide with Stimulatory Effect of Low Partial Pressures. 

 Carbon Dioxide considered as a Narcotic Agent. 



From the experiments already described it is definitely shown that the 

 phenomenon of non-germination induced in the seed by CO2 is one of 

 temporary inhibition resulting in a condition strikingly similar to that of 

 narcosis. The interesting question therefore presents itself as to how far 

 this depressant action of carbon dioxide can be regarded as true narcosis. 



Looking back, in the first place, through the history of previous work, it 

 has to be noticed that the following results have been recorded as to the 

 effect of carbon dioxide on the growth activity of plants : — 



De Saussure (3) in 1804 found that an atmosphere containing 8 per cent. 

 CO2 restrained the growth of peas. Montemartini (4) found that over 7 per 

 cent. C0 2 depressed the growth activity in the roots of peas. Chapin (5) in 

 1902 confirmed this. Bohm(6), Dr. Drabble (7), Prof. Farmer (1), and 



