A. MARTINELLI ON THE GERMINATION OF A SEED. 15 



non-living from the fact that if a germinating seed is exposed to the 

 vapour of ether, growth is immediately arrested, although the 

 evolution of carbonic acid gas, and the conversion of the carbonaceous 

 substance into dextrin and sugar still continue. On the other 

 hand, etherisation at once suspends the protoplasmic functions of the 

 yeast ferment, and from saccharine fluids no carbonic acid is evolved 

 nor alcohol produced. Diastase may be extracted from malt by the 

 chemist as a white soluble substance. It is, however, so subject to 

 change that it cannot be preserved ; it has never even been obtained 

 in any definite condition for analysis. 



Its powerful action is best illustrated in the case of brewer's 

 grains. When the starch has been converted into dextrin and 

 sugar, a large percentage of the granular fibrin (from which the 

 diastase has been evolved) remains intact — showing with what a 

 small expenditure of force this metamorphosis is effected. Further, 

 if unmalted grain is mixed with malted grain, it is found that the 

 carbonaceous or starchy matters of both are changed into a form of 

 sugar. Subsequent examination shows the fibrin of the unmalted 

 grain unaffected by the process it has undergone, but that of the 

 malted grain appears to have almost wholly disappeared. Hence we 

 may infer that the transformation has been effected by the decom- 

 position of the granular fibrin of the malted grain. 



To this it may be added that the evolution of diastase and the 

 conversion of starch into sugar by artificial means attains its maxi- 

 mum only by a temperature sufficiently high to destroy all vegetable 

 life, viz., 70°C. But under natural conditions diastase is evolved at 

 from 5° to 42°C (the extremes). 



The foregoing general remarks may now be of service in dealing 

 with the germination of a bean seed {Phaseolns). If sown in cold 

 wet soil, the sun's heat gives no vitality to the germ, but is lost in 

 evaporating the superfluous moisture ; the starch granules remain 

 undissolved (Fig. 10), and the albuminoids decay. If sown, however, 

 under favourable conditions, the two albuminoids of the bean, casein 

 and albumen, undergo decomposition, and act as ferments in the 

 same manner as the fibrin of barley. In the first stage of germina- 

 tion the outer coating of the seed is softened, and moisture pene- 

 trates its inmost tissues. Gradually the whole seed or embryo 

 attains a high state of tension ; the starch granules become turgid, 

 increase in temperature, and the ferment is set free. Then chemical 

 action is induced in some of the granules, and those contiguous are 



