ANIMAL SENSE PERCEPTIONS. 163 



kind of secretion is that of strong scented ethereal oils. Species 

 of Artemisia are characteristic plants of the deserts of Africa 

 and Beluchistan ; Pulicaria arabica has a particularly powerful 

 odour. " Since Dr. Tyndall has shown how minute quantities 

 of such oils diffused through the air are capable of arresting 

 radiant heat, it has been suggested that this is one of the many 

 resources to which desert plants appeal, in order to reduce the 

 ill-effects of the heated atmosphere which surrounds them ; and, 

 just as the presence and quantity of opium, hasheesh, aconitine, 

 &c, secreted by plants vary greatly with the climate, so it is 

 reasonable, in the absence of strict investigations, to assume that 

 these oils are in an excess through the intense heat and other 

 conditions of the climate of deserts."* This appears to have 

 been first suggested by Dr. Volkens,t and Mr. Henslow would 

 further apply the suggestion to odoriferous plants growing at 

 high altitudes. + These observations or suggestions cannot, of 

 course, have any application beyond the areas mentioned, and, if 

 correct, tend to prove that scents emitted by plants may have 

 other purposes besides those of animal attraction, and again 

 inculcate the necessary caution against concluding that a quality 

 many times observed to have an attractive purpose is necessarily 

 fulfilling that function in all cases. The exhaustive and eloquent 

 summing up of a brilliant judge may excite the admiration of the 

 lounger in court, but does not necessarily have that effect on the 

 litigant whose case it demolishes. Because a plant exhales an 

 offensive odour, it is not less attractive to some insects. In 

 Borneo, Mr. Burbidge found a large amorphophallus bearing 

 fetid flowers ; on cutting one of these open he found its basin 

 " half-full of ants of two kinds, and numerous small black 

 coleoptera were running about in the spathe."§ 



The appreciation of scents and odours by mankind is not of 

 universal similiarity, but varied and capable of artificial dis- 

 tortion. The sense of smell is generally considered as more 

 highly developed in savage than in civilized races. Nevertheless, 

 as Darwin has observed, it does not " prevent the Esquimaux 



t;: Henslow, ' The Origin of Plant Structures,' p. 82. 



f Ibid. p. 116. 



\ Ibid. 



§ 'The Gardens of the Sun,' p. 233. 



o2 



