1 36 RECAPITULATION. 



The cryptogamous theory well explains the obstruction 

 to the progress of malaria offered by a road, a wall, a 

 screen of trees, a veil or a gauze curtain. 



It also accounts for the nice localization of an ague, or 

 yellow fever, or cholera, and the want of power in steady 

 winds to convey malarious diseases into the heart of a 

 city, from the adjacent country. 



It explains also well, the security afforded by artificially 

 drying the air of malarious places, the exemption of cooks 

 and smiths from the sweating sickness, the cause of the 

 danger from mouldy sheets, and of the sternutation from 

 old books and papers. 



On no other theory can we so well account, if account 

 at all, for the phenomena of milzbrand and milk-sickness, 

 the introduction of yellow fever into northern ports, and 

 the wonderful irregularities of the progress of cholera. 



The cryptogamous theory will well explain the pecu- 

 liar domestication of different diseases in different re- 

 gions, which have a similar climate; the plague of Egypt, 

 the yellow fever of the Antilles, and the cholera of India. 

 It accounts, too, for their occasional expansion into unac- 

 customed places, and their retreat back to their original 

 haunts. 



Our hypothesis will also enable us to tell, why malarious 

 sickness is disproportionate to the character of the seasons ; 

 why it infests some tropical countries and spares others ; 

 why the dry Maremma abounds with fevers, while the wet 

 shores of Brazil and Australia actually luxuriate in health- 

 fulness. The prolonged incubative period, the frequent 

 relapses of intermittents, and the latency of the malari- 

 ous poisons for months, can only be well explained by 

 adopting the theory of a fungous causation. 



Finally, it explains the cause of the non-recurrence of 



