Decembbr 12, 1902.] 



SCIENCE. 



925 



rately, but in combination as formaldehyde. 

 The higher carbon acid, to which Bach 

 ascribes the formula IIjCO^, splits up into 

 carbon dioxide and hydrogen peroxide, and 

 the latter is decomposed into water and 

 free oxygen. 



Lieben has still more recently put for- 

 ward the view that formic acid and not 

 formaldehyde is formed by the first decom- 

 positions. He has found that leaves of 

 grasses and various trees yield formic acid 

 among other products when mixed with 

 their own weight of water containing a 

 trace of sulphuric acid, and distilled with 

 steam. Moreover, when carbon dioxide 

 is acted upon by nascent hydrogen the only 

 product is formic acid. 



These speculations afford many points 

 which might be well made the starting 

 places of research. The views of Baeyer 

 have met with most acceptance, though but 

 little success has attended the few efforts 

 that have been made to establish them by 

 experiment. 



They involve several definite stages of 

 action, of which the most important seem 

 the production of carbon monoxide and 

 hydrogen, the formation of formaldehyde, 

 and the construction of a sugar. The last 

 two questions arise also in connection with 

 the hypothesis of Bach. 



If we examine the work that has been 

 published bearing on the probability of the 

 formation of carbon monoxide in the plant, 

 we find little that is satisfactory. The 

 statements that have been made are op- 

 posed to the idea that carbon monoxide is 

 of value in nutrition ; it is said that when 

 supplied to a plant instead of carbon 

 dioxide it does not lead to the formation of 

 carbohydrates. It is further advanced 

 that this gas is of a very deleterious nature, 

 and if formed would result in the speedy 

 death of the protoplasm of the cell in 

 which it originates. This idea is, of course, 

 specious; but it does not appear to be well 



founded. The deadly character of carbon 

 monoxide when inhaled by a human being 

 depends upon a peculiar interference which 

 it causes with the oxygen-carrying power 

 of the red blood corpuscles. The pigment 

 hemoglobin to which these little bodies owe 

 their usefulness forms a loose chemical, 

 combination with oxygen, the compound 

 being formed in the blood vessels of the 

 lungs and being decomposed with the liber- 

 ation of the oxygen in those of the tissues 

 of the body. It is evident, therefore, that 

 the value of the corpuscles as oxygen-car- 

 riers depends upon their haemoglobin. 

 "\\nien this pigment is exposed to carbon 

 monoxide it combines with it in the same 

 ■way as it does with oxygen, forming, how- 

 ever, a more stable compound. The affinity 

 for this gas which the pigment manifests 

 is very considerable. Hence the poisonous 

 nature of carbon monoxide. It is easily 

 seen that the latter is a poison because it 

 throws out of gear and temporarily para- 

 lyzes a most essential part of the mechan- 

 ism of respiration, effectually preventing 

 oxygen from reaching the tissues of the 

 body. There is no evidence here that it 

 exerts even a deleterious influence upon the 

 living substance itself. The only poisonous 

 effect it would be able to exert on the plant 

 would necessarily be of the latter character, 

 for there is no oxygen-carrying mechanism 

 that could be interfered with. "We cannot 

 lay any stress, therefore, on the objection 

 to Baeyer 's view, based upon the action of 

 carbon monoxide upon the human organism. 

 Another possibility may, however, be 

 mentioned. As we shall see later, there are 

 certain resemblances between haemoglobin 

 and chlorophyll, the vegetable pigment con- 

 cerned in photosynthesis. May not carbon 

 monoxide enter into some relationship with 

 the latter, and thereby indirectly hinder its 

 activity? Of that, however, there is no 

 reliable evidence, the facts known to us 

 rather pointing in the opposite direction. 



