104 Mr. T. Hopkins's Observations on Malaria. 



tensity. It is easier to accustom a plant of the lowlands to 

 this elevation than to bring down those of the paramos. Thus 

 the orange and lemon trees, Aguacates {Launis persea) Iti- 

 cimis comimmis, Datura arhorca, all natives of the hot low- 

 lands, grow and flourish, more or less, at an elevation of 

 8000 feet above the level of the sea. 



[To be continued.] 



XX. Observations 07i Malaria, tioith Suggestio?is Jbr ascertain- 

 ing its Nature : read before the Literary and PJtilosophical 

 Society of Manchester.^ November 15, 1838. By Thomas 

 Hopkins, £sy.* 



MALARIA is considered the scourge of a considerable 

 portion of Italy, where it is spoken of with an undefin- 

 able feeling of horror. It is not, as its name may seem to 

 impl}', supposed to be simply bad air, but a poisonous efflu- 

 vium arising from some undiscovered operation of nature, 

 and known only through its dreadful effects on human beings. 

 The volcanic nature of the country, the gases thrown from its 

 surface by the agency of internal heat, with their offensive 

 smells, are in the imagination of the people connected with 

 the cause of marsh fever, and designated by the word Mal- 

 aria. The author of the description of Latium speaks of 

 the volcanic soil being prejudicial to the atmosphere; and 

 Mrs. Starke, in her account of Rome, talks of the sulphur, 

 arsenic and vitriol which abound, producing malaria. This 

 lady may be considered as speaking the ordinary language of 

 the people of the country on the subject. Learned writers too 

 have treated of malaria in a way almost equally mysterious, 

 among whom may be named Dr. Macculloch. The Doctor 

 does not indeed suppose that sulphur or vitriol is instrumental 

 in producing the poison, but that it is the product of vege- 

 table fermentation or putrefaction, the form and mode of 

 operation of which we are not able to trace, becoming con- 

 scious of its existence only by witnessing its effects. The 

 pest is shown to be worse in Italy than in other parts of 

 Europe, but the Doctor has shown that it really prevails in 

 other countries, and to a greater extent than had been pre- 

 viously suspected. Whatever may be the peculiar nature of 

 malaria, Dr. Macculloch seems satisfied that it does not arise 

 from the presence of minerals, nor from local causes confined 



* Communicated by the Author. The reader may advantageously 

 compare this paper with Mr. Addison's " Bemarlcs on the Infiuence of Ter- 

 restrial Radiation in determining tlie site of Malaria" Pliii. Mag. and An- 

 nals, N.S., vol. iv. p. 272, et seq. — Edit. 



