i66 EXPERIMENTAL GARDEN 



2. That plants give out more oxygen during the day than 

 they absorb at night. Philosophical Transactions, 1836. 



3. That the more luminous rays of the solar spectrum 

 are especially instrumental in stimulating the vital energies 

 of plants, thus causing them to absorb moisture by their roots, 

 to exhale it from their leaves, and to emit oxygen through 

 the decomposition of carbonic acid gas. Philosophical Trans- 

 actions^ 1836. [Anticipation of Draper's discovery.] 



4. That some of the ingredients of a soil are active, whereas 

 others are dormant, i.e. a portion only of the mineral matter 

 in a soil is in a condition to be taken up by a plant. 

 Ploughing and other agricultural operations seem to be mainly 

 of utility in promoting the gradual operation of atmospheric 

 agents, in unloosing the dormant ingredients from their union 

 one with the other, and in thus rendering them available for 

 the purposes of the plant. Botanic Lecture, 1843; Journ. 

 Royal Agric. Soc., 1846. 



5. That the rotation of crops is advantageous. Baker ian 

 Lecture', Philosophical Transactions, 1845. 



6. That the mineral phosphates of Estremadura in Spain are 

 most efficacious as a manure. Journ. Royal Agric. Soc., 1846. 



7. The relative utility of certain manures. -British Associa- 

 tion Reports, 1846; Agricultural Notes, 1846. 



8. That ferns can subsist for a limited time in an atmo- 

 sphere containing no less than 20 per cent, of carbonic acid 

 gas, and, since the cold-blooded animals which were associated 

 with the plants of the coal formation could in all probability 

 also endure an atmosphere containing 50 per cent, of this 

 gas, there is nothing contrary to probability in the supposition 

 of M. A. Brongniart, that at this early period a larger amount 

 of CO 2 existed in the atmosphere than is present in it now. 

 British Association Reports, 1848. 



9. That the relative proportions of potash and soda vary 

 in barleys grown in plots artificially impregnated with these 

 alkalies. -fourn. Chemical Society, 1853. % 



