450 General Notices. 



MISCELLANEOUS INTELLIGENCE. 



Art. I. General Notices. 



The fiscal Excretions of Plants. — The committee of botany of the British 

 Association for the Advancement of Science have requested Professor Daubeny 

 of Oxford, " to institute an extended enquiry into the exact nature of the 

 secretions by the roots of the principal cultivated plants and weeds of agricul- 

 ture ; and that the attention of botanists and chemists be invited to the degree 

 in which such secretions are poisonous to the plants that yield them, or to 

 others; and to the most ready method of decomposing these secretions by 

 manures, or other means." Dr. Lindley has also proposed the same thing as 

 a desideratum. 



The Cause of Malaria, in the pestilential districts of Italy, has generally 

 been supposed to be the decomposition of vegetable matter on a moist surface. 

 This, however, is to confound the malaria with the marsh fever. The former 

 is now thought to proceed from a very different cause, and to be analogous to 

 what in England is called the hay fever. It is found that, while the corn or 

 hay crop is in a growing state in the pestilential districts, they are as healthy 

 as any part of Italy ; but that, the moment the crop is cut down, or withers 

 on the ground, the malaria commences, and continues through the autumn 

 and winter, till vegetation becomes vigorous in the following spring. The 

 neighbourhood of Rome, where malaria is so prevalent, " is very hilly, dry, 

 and entirely without vegetation. For days together, one sees nothing but 

 desolate dried up corn fields, without trees, bushes, or wood of any description. 

 In early times, Rome was surrounded by extensive sacred woods, which were 

 not suffered to be destroyed. At that period malaria was unknown, though 

 intermitting fevers were well known in the Pontine Marshes. The avarice of 

 the popes, however, converted these sacred woods into gold, and so desolated 

 the region that not a tree or wood is to be met with around Rome. With 

 the commencement of this system of extirpation the malaria appeared, and 

 has at length reached such a height, that, yearly, many are carried gradually 

 off by it; and, in the summer months, strangers and respectable inhabitants 

 quit Rome. When we take into consideration all the phenomena of marshy 

 districts, the conclusion does not lie far distant, that the atmosphere is in 

 different degrees rendered unfit for human organisation, not by the passage of 

 the water to the air, but by the decomposition and solution of vegetable sub- 

 stances; and that thus those various intermitting fevers, and even the plague 

 itself, are produced. In the case of real malaria, in opposition to marsh fevers, 

 the circumstances are different. So long as the earth is covered with living 

 vegetables, as, for example, with corn, the air of the most suspected district 

 is pure and healthy, and no one fears being attacked by the disease ; but, when 

 the prodigious crops, which in those volcanic loose-soiled districts are speedily 

 brought to maturity, are removed, does the surface of the earth become dead 

 at the warmest and most energetic period of its functions ? or does not rather 

 a portion of those substances, which were consumed by the leaves and roots of 

 plants, now go to the atmosphere, and render it unfavourable for the breathing 

 of man, until all is again restored to an equilibrium in higher or more distant 

 regions ? That carbonaceous matter is beneficial to the vegetable kingdom, is 

 as well known as that it is prejudicial to the breathing process in animals. No 

 educated person in Germany doubts the organic function of the earth, to 

 which also the cholera itself has been ascribed; and when a more general 

 regard to nature advances to the south, the sacred woods will again gradually 

 surround Rome, large vine branches entwine themselves round the elms, the 

 hills be thus again covered, and the malaria reduced within limits. The fact 

 is not without interest, that all real malaria districts are of volcanic formation, 

 and that they are often to be found at the boundary of volcanic and non- 



