BAEYER'S THEORY 57 



Considering the first part of Baeyer's theory, it is seen that 

 both carbon monoxide and hydrogen are supposed to be pro- 

 duced, but carbon monoxide has been found but once in a 

 free state in the living plant (p. 105), and it is a substance which 

 does not lend itself at all readily to constructive metabolism, 

 the evidence as to whether plants are able to make use of it 

 for synthetic purposes being contradictory. Bottomley and 

 Jackson * state that if the carbon dioxide normally present 

 in the atmosphere be replaced by about twenty times as much 

 carbon monoxide — the increase in the amount of the latter 

 being necessary on account of its lesser solubility in water 

 as compared with carbon dioxide — plants of Tropceolum 

 formed starch and flourished. Preliminary analyses also 

 showed that seeds, when germinated in an atmosphere in which 

 the carbon dioxide had been replaced by carbon monoxide, 

 there was an increase of organic carbon in the seedlings. 

 Further, they found that a negative pressure obtained in the 

 vessels containing the plants assimilating carbon monoxide. 

 This was to be expected if the hypothesis be accepted, for if 

 the carbon monoxide be used up in photosynthesis, then the 

 amount of oxygen set free would be half that evolved in normal 

 photolysis. On the other hand, Krasheninnikoff f has come 

 to the conclusion, based on a number of experiments, that 

 green plants cannot make use of carbon monoxide ; he points 

 out, however, that his evidence does not prove that carbon 

 monoxide is not formed in the early stages of photosynthesis. 

 It may also be remarked that according to the investigations 

 of Sulander,i carbon monoxide acts as an anaesthetic, but is 

 much weaker in its action than chloroform. He found that 

 0-5 per cent, of this gas was sufficient to inhibit the growth 

 of seedlings of the lupin and the germination of the spores of 

 many Fungi. On the other hand, Wehmer§ found that the 

 seedlings of cress and barley are not injured by exposure 

 to an atmosphere containing 50 per cent, of carbon monoxide. 



* Bottomley and Jackson : " Proc. Roy. Soc," B, 1903, 72, 130. 

 t Krasheninnikoff : " Rev. gen. Bot.," 1909, 21, 177. 

 X Sulander : " Beih. bot. Centrbl.," 1909, 24, I., 357- 

 § Wehmer : '* Ber. deut. bot. Ges.," 1925, 43, 184. 



