CH. I.] SOWING. 37 



to the cotyledonous parts of the seed, as is e\-ident 

 by the changes which take place during gennination : 

 and it is fmlher proved by experiment. TMien 

 healthy seed is moistened and exposed in a suitable 

 temperature to atmospheric air, it absorbs the oxygen 

 only. This power of separating one gas from the 

 others, appears to reside in the integuments of the 

 seed, for old seeds lose the power of absorbing the 

 oxygen and consequently of germinating ; yet they 

 will frequently germinate if soaked in an aqueous 

 solution of chlorine — a gas wliich has the power of 

 attracting hydrogen from water, and others of its 

 compounds, and releasing the oxygen, doing so in 

 the case of seeds ^vithin their integuments as well as 

 withoutside. Humboldt and Saussure have also 

 she\vn that the application of chlorine to seed ac- 

 celerates its gennination, and cress seed, which, under 

 ordinaiy cu'cumstances, requires some days to com- 

 plete the process, they found e£fected it in no more 

 tlian three houi's. The late Mr. George Sinclair, 

 author of the excellent Hortus Gramineus Wo- 

 hurnensis, also informed me that he employed 

 chlorine with singular success. He obtained it by 

 mixing a tablespoonful of miu-iatic acid ^vith a similar 

 quantity of black oxide of manganese, and half a pint 

 of water. After allo^^ing the mixtm'e to remain two 

 or three hours, the seed is to be immersed in the 

 liquid for a similar period, and then sown. Another, 



