OUR HOMES. 35 



There is one very interesting' aspect of this question, which has 

 relation to the influence of trees upon health. Reference was 

 made to it in the lecture, and some instances given. A very in- 

 teresting illustration of the effect gf trees in arresting malaria 

 was mentioned by J^ Stanton Gould of New York, at the Farmers' 

 ConA^ention, held in Manchester, N. H., a short time ago. Near 

 Annapolis, Md., there is an asylum at which, a few years ago, 

 cholera prevailed. It seems that near this asylum there was a 

 cesspool, into which the sewerage of the asylum and of 'the sur- 

 rounding buildings was drained, and between this cesspool* and 

 the asylum was a clump of trees, in a certain position. The mat- 

 ter was investigated, and it was found that it was the custom to 

 allow the windows on the side of the building towards the trees 

 and the cesspool to be opened during the day, and that all the 

 cases of cholera were in those rooms between which and the cess- 

 pool no trees intervened. Those rooms that were in a line with 

 the cesspool and the trees, so that the trees were between the 

 windows and the cesspool, were entirely exempt from cases of 

 cholera. The trees seemed to arrest the malaria, so that it did 

 not develop itself in those rooms, but in all the others there was 

 disease. I think there have been other cases recorded where trees 

 arrested malaria in a similar way. 



Trees undoubtedly act also in purifying the air, not only direct- 

 ly as arresters or absorbers of material deposits, but in their 

 chemical relations, by purifying the air, as has been noticed by 

 Mr. Chamberlain, in removing carbonic acid from the air, appro- 

 priating the carbon to their own growth, and throwing off' the 

 oxygen into the air. Indeed, the only known Source of the supply 

 of oxygen to the air, which is being constantly taken from it by 

 combustion, by expiration, by putrefaction, by the processes of 

 decay — the only known means by which this supply is maintained, 

 is through the action of vegetation in absorbing carbonic acid and 

 returning oxygen to the air. This process, as has been stated, 

 goes on most completely under the influence of the sun, whereas, 

 during the night, it is arrested, or the reverse process takes place ; 

 so that the question which frequently arises, "Are flowers in a 

 room a source of health?" may be ansvv^ered, in brief, in this way : 

 During the day time they are. They take up noxious vapors, they 

 decompose carbonic acid, which they absorb, and appropriate the 

 carbon and give forth oxygen to the air, thus purifying the air. 

 During the night, this process is ai-rested or reversed in a measure ; 



