342 DR. ANGUS SMITH ON PEAT. 



wholesome class of swamps and marshes into sanitary 

 agents. It is pretty well known that decomposing matter 

 gives out gases and emanations which produce many forms 

 of disease ; but I do not know if it can he proved that 

 malaria, which produces its peculiar class of fever and of 

 ague, can be said to arise entirely from a decomposing 

 body or the products of decomposition ; the evidence 

 points also to living plants and to substances arising from 

 them. I will not attend to this question at present, 

 because in either case we find that the peat-bog has the 

 advantage. If it be the living plant, we find no malaria, 

 no fever, no ague caused by peat ; if it is the peculiar 

 class of plants, mosses, sphagnums, heaths, or whatever else 

 grows there, which causes freedom from these evils, then 

 let us cultivate that plant. On this point Macculloch 

 says that malaria " is notoriously not produced by dead 

 peaty bogs or by peat which carries no vegetation " (p. 61, 

 ' On Malaria/ by John Macculloch, M.D., F.R.S., 1827). 

 Immediately after, however, he says that it would be easy 

 to show that peat lands are not exempt from malaria when 

 there is vegetation enough ; and he attributes the absence 

 of malaria on growing peat-bogs to the cold. If, however, 

 we look at the limits of malaria, we find it about St. Peters- 

 burg with a mean temperature of 3°'38 R., or 39°*6 P. 

 (from Muhry's ' Klimatologische Untersuchungen/ 1858). 

 In Oesterlen's ( Handbuch der Hygiene/ we have the 

 limit put as 5 C, or 41 ° F. (edition of 1857), which is 

 considerably lower than the mean temperature of Edin- 

 burgh and Dublin. 



Macculloch supports me so far in saying that gases do 

 not come from formed peat ; he is inclined to think that 

 the plants may produce malaria in decomposing. The 

 temperature may influence the character of the plant, also 

 the character and speed of its decomposition ; but when the 

 plant is transformed into peat, the great fact that the 



