428 THE POPULAR SCIENCE MONTHLY. 



no epidemic in these houses, although it prevailed largely immediately 

 beyond the English Garden and close to the Diana Baths in 1854 and 

 1873. It must have been accidental that no isolated cases occurred, 

 as the inmates of the Chinese Tower, or the Kleinkessellohe, might 

 have caught it in Munich as others did who came from a distance, 

 but, had there been single cases, probably no epidemic would have 

 occurred in these houses. 



Even if these deductions must be accepted with caution from an 

 etiological point of view, still, on the whole, they indisputably tell in 

 favor of trees and woods. 



Surface vegetation has also other advantages, besides its use in 

 regulating the moisture in the soil ; it purifies it from the drainage of 

 human habitations, whereby it is contaminated and impregnated. If 

 this refuse matter remains in soil destitute of growing vegetation, 

 further decomposition sets in, and other processes are induced, not 

 always of a salubrious nature, but often deleterious, the products of 

 which reach us by means of air or water, and may penetrate into our 

 houses. But from this indisputable fact false conclusions are some- 

 times drawn. Many people imagine that if a few old trees are left 

 standing in an open space their roots will absorb all the impurities 

 from the houses around, and render the refuse which accumulates 

 beneath them innocuous. This idea is not only false in a sanitary 

 point of view, but very injurious, as it prevents people from taking 

 the measures which alone can keep the ground under our houses 

 pure. 



We will now explain why the shade of gardens and woods is at 

 certain seasons so beneficial. The human race during its pilgrimage 

 on earth and wanderings over it has many difficult tasks to perform. 

 One of the most difficult is involved in the necessity that all our in- 

 ternal organs, and the blood, whether at the equator or the north- 

 pole, should retain an equable temperature of 37^ Centigrade (98 

 Fahr.). Deviations of but one degree are signs of serious illness. 

 The blood of the negro and that of the Esquimaux is of the same tem- 

 perature, while the one lives in a temperature of 40 above, and the 

 other 40 below zero (Centigrade). A difference of 80 has therefore 

 to be equalized. 



Our organism, doubtless, possesses a special apparatus for the per- 

 formance of this colossal task, self-acting sluices so to speak, by means 

 of which more or less of the heat generated in the body passes off: 

 these consist mainly in the increase or diminution of the peripheric 

 circulation, and the action of the pores of the skin. But we soon come 

 to the end of our natural regulating appai - atus, and have to resort to 

 artificial means. Against cold we have excellent methods in clothing, 

 dwellings, and fires ; but at present our precautions against heat are 

 very limited. This is, doubtless, the reason why higher civilization 

 has extended so much farther toward the polar regions than toward 



