14 



view I may also meutiou that many flowers aud fruits, and especially 

 also some animal products, have a totally different smell at different 

 distances from the nose. Musk and civet are remarkable instances of 

 this ; they are veiy agreeable to some persons when in very slight 

 quantities or at a distance, but to the same persons these perfumes are 

 positively nauseous when too near, or in too large quantities. Another 

 reason 1 may perhaps be allowed to advance is, that in the case of 

 some plants it is absolutely necessary that the surrounding air must be 

 perfectly still, or they become scentless, even though the only motion 

 of the air be a current made by endeavouiing to draw the perfume up 

 the nose. This is particularly exemplified by the musk plant Mimuhis 

 7noschatus, which it is well known has a beautifully deUcate odour of 

 musk, but if we attempt to smell it a second time we find it less per- 

 fumed, and after the thii'd time we can perceive no odour whatever. I 

 am of course supposing that this proceeding only occupied two or three 

 minutes. I have still another argument to offer, and that is the 

 remarkable fact that all the perfumes at present knowTi may be referred 

 to a very few types ; thus the heliotrope may be taken as one tj'pe, and 

 we find the meadow-sweet ( Sjnrera ulmaria), the hawthora, the sweet 

 scented coltsfoot, and many others closely resemble it. The violet may 

 be taken as another type, and we find the root of the Iris jiorentina and 

 a few other plants, especially some of the tui-pentine-producing conifers, 

 also yield a similar odour. This would seem to imply a greater 

 regularity of the action producing the sense of smell, than we can 

 suppose would be caused by the racUation of atoms from so many 

 different species. 



In conclusion, I beg to remark that the most careful microscopic 

 examination with the highest powers fail to detect the eUmination of 

 particles, although we can detect the motion of the contents of cells, 

 and changes pi'oduced by oxygenization. 



I am at present engaged in endeavouring to classify vegetable odours 

 under well known types, and if I have the privilege at some future 

 time of returning to this subject, I shall hope to have a large and 

 satisfactory Ust of perfumes so arranged. 



