284 Marshes. [Nov., 



free from intermittents, were once abounding in them. The pro- 

 gress of agriculture has in many instances entirely banished this 

 severe disease, and so as good husbandry extends a two fold in- 

 fluence, beneficial in its character is sure to follow healthfulness 

 and wealth. Man never benefits himself in a legitimate way, 

 without doubling his blessing, first receiving them into his own 

 bosom, and then that of his neighbor. It is not however at all 

 essential that a marsh or pool should exist, in order that poison- 

 ous vapor should be generated. Animal and vegetable matters in 

 combination in deep mould, such as is found in the western prairie 

 is sufficient to generate a pestilence when exposed to the sun beams, 

 and when moistened merely with dew, is sufficient in itself to 

 form the miasm and float it in the atmosphere. Turf new plough- 

 ed, or turned over, especially if the areas are large, turns a coun- 

 try before healthy, into a region of sickness. From researches 

 which have been instituted by Thenard and Dupuytren, Moscati, 

 and by M. Regaud d 1' Isle, the miasmatic exhalations have been 

 found to contain animal matter, and hence it is probable that it is 

 really composed of both animal and vegetable matter. It has 

 been shown by Vauquelin, that the exhalations from the Pontine 

 marshes aflforded animal matter in a putrescent state. In the fore- 

 going instances however, this matter was obtained from the wa- 

 ter or soil, but Boussingault succeeded in obtaining it from the 

 atmosphere over the great southern American marshes, a fact 

 which goes to show that the poisonous eflfluvia is exhaled in a 

 tangible state. These poisonous gasses contain in addition to an- 

 imal matter, light carburetted hydrogen, azote and carbonic acid, 

 and sulphuretted hydrogen, and sometimes a trace of phosphuret- 

 ted hydrogen. By vaporization of dew in the rains upon our 

 western prairies, and the water of marshes, these organic and 

 poisonous effluvias are disseminated in the atmosphere, and are 

 wafted by the breeze over wide areas. 



An interesting and important fact may be stated in this place, 

 viz. that age influences or modifies the effects of marsh miasm. 

 Infants or children under two, are less affected than those of three 

 or four years. This may arise from the greater exposure of the 

 latter. So old persons are less affected than those of middle age, 

 or who are engaged in artisan pursuits. Children when attacked 

 with disease fall victims to its influence, more easily than adults; 

 their mortality is greater in the proportion of 1000 to 1546, and 

 it has been observed that fewer deaths occur in infants below one 

 year than in those of three or four years; after ten years the in- 

 fluence of marshes is less to be feared, and the capability to resist 

 marsh miasm increases up to twenty-five years, from twenty-five 

 to fifty-five the susceptibility again increases, though it is never 

 so great as in children between the ages of two and ten years. 



