oy late spring frosts, and by other causes that botanists have not 

 yet fally determined. In localities where the winters are mild 

 and the soil deep, this tree grows too rapidly and is easily split by 

 winds of moderate velocity. It should also be borne in mind that 

 it is frequently very expensive to grow this tree. For instance, if 

 the soil be very wet, it is necessary to drain it ; otherwise the 

 roots of the tree rot. If, on the other hand, the soil be very stiff, 

 it is necessary to dig deep holes to make room for the roots, which 

 holes require to be drained to prevent water from standing in 

 them and rotting the roots. It is, therefore, more prudent to hold 

 to methods less uncertain, and when the condition of a locality 

 indicates the advisability of planting trees for the absorption of 

 moisture, it is better to set out trees belonging to our hemisphere. 

 It is less expensive, and there is less likelihood of the ttees dying. 



" One of the most generally accepted theories is that forest* 

 produce malaria independently of the quality of the soil which 

 they cover. On every hand we meet with forests in which the 

 production of malaria is most abundant, and we find on every 

 hand vast tracts of country which remained uninhabited by reason 

 of malaria bo long as they were wooded and that became more or 

 less completely healthful upon being cleared. These facts are 

 interpreted as showing that malaria is produced in the forests by 

 the putrefaction of the leaves, branches, and dead insects that 

 become accumulated on the ground and there slowly decompose. 

 But such an explanation cannot stand, because, were such the 

 case, we ought to meet with malaria in every forest of the world, 

 where decomposition of organic detritus occurs, whereas, on the 

 contrary, many forests are free from malaria. Forests are factors 

 of malaria in an indirect way only ; they do not produce it 

 themselves, but favour its development whenever they cover lands 

 that are malarial. They intercept the solar rays, and hence prevent 

 an active evaporation from the soil, so that it retains a great deal 

 of humidity in the warm season. If the soil does not contain the 

 malarial ferment, the forest is not infected and vice versa. Malarial 

 forests are frequently met with in nature, and the clearing away 

 of these forests has rendered the localities occupied by them much 

 more healthful, if not entirely so. 



" Dr. Montechiare, a practising physician of Rome who for years 

 was physician to the penal colony at " Tre Fontane, ' tells me that 

 his experience justifies him in declaring that no beneficial result 

 against malaria has been derived from the planting of the 

 Eucalyptus, The monks set out no less than 50,000 trees on a 

 few acres. Had the efficacy of the Eucalyptus proven real, the 

 entire settlement of the " Tre Fontane " would have become a 

 veritable Eden on account of its wholesome, balsamic air, which 

 has by no means been the case. In 1870, Dr. Montechiare, being 

 in charge of St. John's Hospital, experimented with all the 

 preparations of Eucalyptus against malarial fever, and found ttat 

 not one lowered the temperature of the patient by a tenth of a 

 degree. The only value of the elixir of Eucalyptus consists in 

 the alcohol that it contains. The efficacy of the Eucalyptus for 

 the improvement of the air is no greater than that of the elm, pine, 

 and mulberry. If it recommends itself by its rapidity of ^owth, 

 the trees just mentioned recommend themselves by bemg hardier 

 and more easily grown. 



