Atkins — The Absorption of Water by Seeds. 45 



Note on the Colouring Matter of Beans. 

 It was observed in titrating that the colouring matter of the beans 

 originally in acid turned purple with alkali, forming au accurate end-mark 

 as tested with phenolphthalein. The purple colour is due to a gelatinous 

 precipitate, which is dark-brown when seen on filter-paper, the filtrate being 

 a deep red when alkaline, almost colourless when acid. Tlie precipitated 

 colouring matter dissolves in dilute acid, giving an orange-yellow solution. 



Experiments on the first Appearance of Respiration in Seeds. 

 It was thought that it might be legitimate to use the production of CO2 

 by seeds as a test for the beginning of active cell-metabolism, and consequently 

 the end of the period of latent life. Accordingly, about two hundred beans, as 

 bought, were sterilized outside by placing in a strong solution of mercuric 

 chloride for several minutes, and then well rinsed with distilled water. This 

 procedure does not injure the seeds ; for 98 per cent, subsequently germinated. 

 They were then placed in a conical flask similarly sterilized, completely 

 filled with distilled water. This had a rubber cork, and a long and short 

 glass tube. A current of air was passed by a force-pump through a Greissler 

 potash bulb, and through a second bulb witli barium-hydroxide into the 

 conical flask, which was tilted so that the water trickled out slowly as the 

 CO2 free air entered. This was continued till only a little water remained — 

 just enough for tlie beans to imbibe. The tube througli which the water 

 had flowed was tlien connected to a barium-hydroxide bulb joined to 

 another Geissler potash bulb. Two clips closed the tubes leading to the 

 flask. A number of such experiments were performed ; and the time that 

 elapsed before CO2 could be detected on removing the clips and passing in 

 purified air was gradually narrowed down till it was detected with 

 certainty two hours after tlie moistening of the seeds with mercuric chloride 

 solution, though a slight turbidity appeared in the barium hydroxide bulb 

 on the exit an hour and a quarter after moistening. The great difficulty of 

 obtaining a perfectly clear solution of this hydroxide is the cause of the 

 uncertainty. Identical experiments with a saturated solution of chloroform 

 in water as the moistening liquid gave a copious precipitate of BaCOa after 

 eight hours, though none of the chloroformed seeds germinated. This gives 

 us reason to believe that the evolution of CO2 cannot be taken as an 

 indication of the renewal of living cell-metabolism ; and tlms the only ready 

 chemical test that can be applied is useless. I subsequently found that 

 F. Steward' has shown that this evolution of CO2 may, partly at any rate, 



1 Ann. Bot., xxii., 1908, p. 415. 



