June 1900.] BOTANICAL SOCIETY OF EDINBURGH 327 



The enormous respiratory acceleration which normally 

 accompanies the germination of resting organs is, however, 

 made very obvious by the rapid decoloration of the 

 fluid which takes place when a tube containing buds 

 is exposed to light. A comparison of such a tube 

 with a control tube containing an equal quantity of the 

 same fluid, and an equal number of buds, of as nearly 

 as possible the same size, and kept under identical 

 conditions, but in darkness, shows that while at first 

 the effect of illumination in accelerating carbon excretion 

 is but small, as the contents of both tubes remain almost 

 identical in tint for the first twelve hours, an enormous 

 increase soon takes place in the amount of carbon dioxide 

 formed, as is made apparent by the rapid decoloration 

 of the illuminated tube, the fluid in which is generally 

 entirely bleached within forty-eight hours, while the rose- 

 red tint is still recognisable in the protected tube at 

 the end of a week, and decoloration is seldom complete 

 till after the elapse of from eight to ten days. 



Exactly similar phenomena occur in flasks prepared 

 in the same way, but left freely open to the atmosphere 

 through the medium of soda lime tubes, which protect 

 the contained fluid from the entrance of atmospheric 

 carbon dioxide, showing that the somewhat limited volume 

 of oxygen contained in the sealed tubes cannot in any 

 way affect the process. 



No increase of carbon excretion is. however, shown 

 in the case of buds enclosed in an atmosphere of pure 

 hydrogen, where intramolecular respiration aloue is possible, 

 and in such cases decoloration takes place even more 

 slowly than in darkness, while not unfrequently the buds 

 die before that process is complete. 



That this loss of tint in the phenolphthalein solution 

 is due to carbon dioxide, and not to the formation of 

 any organic acid by the buds, is easily proved by re- 

 boiling a tube which has been opened after complete 

 decoloration, when the original tint gradually returns 

 as the carbon dioxide is driven off. 



During germination the proteid substance contained 

 in the cells of the bud seems to be but little, if at all, 

 affected, as the xanthoproteic reaction is almost as well 



