184 PHYSIOLOGY CHAP. 



after fatigue by tincture of iodine he was able to distinguish ether 

 and ethereal oils naturally, and oil of cedar, turpentine, bergamot, 

 and cloves somewhat less distinctly ; his smell was, on the contrary, 

 considerably blunted for alcohol and copaiba balsam. After fatigue 

 by copaiba balsam he was alile to distinguish ethereal oils, ether, 

 and camphor. On the other hand, after losing his sensibility to 

 camphor, he could no longer smell eau de cologne, oil of cloves, or 

 ether. The results of fatigue by ammonium sulphide were more 

 surprising: sensibility remained perfect, or almost so, for ethereal 

 oils and cumarine, but was absolutely lost for sulphuretted hydrogen, 

 hydrochloric acid (7 drops in 50 of water), and bromine (1 in 1000). 

 Aronsohn concluded from this that ammonium sulphide, sulphur- 

 etted hydrogen, and the halogens form a single class of odours 

 with the same specific energy. He concluded that different 

 qualities of odours affect different parts of the olfactory nerve. 



Zwaardemaker and Nagel carried out similar experiments. 

 If two odorous substances that do not affect each other chemic- 

 ally, e.g. cumarine and vanilliue, in aqueous solution, are mixed 

 in such proportions that tin- scent of vanilla alone is perceptible, 

 then, after exhausting the sensibility of tin- olfactory organ to 

 the latter, the odour of cumarine alone remains perceptible on 

 sniffing the mixture. This result leads to the conclusion that 

 different specific energies underlie the two odours named, although 

 in Zwaardemaker's classification they belong to the same class, 

 even to the same subdivision of odours. . 



Attempts to support the theory of a number of specific olfac- 

 tory energies have been made from the effects of certain local or 

 general poisons. Frbhlich found that on sniffing at 5 grms. 

 morphia mixed with sugar, smell was perceptibly blunted. If 1 

 cgrm. strychnine and sugar is held in contact with the Schneideriau 

 membrane for 20 minutes a profuse secretion of mucus is produced, 

 which lasts eight days ; there is a simultaneous exaggeration of 

 olfactory acuity. Internal use of strychnine also produces hyper - 

 osmia. The internal administration of atropiue and daturine, on 

 the contrary, inhibits the power of differentiating between odours 

 for several hours. 



Experiments on the partial anaesthetising of the olfactory 

 mucous membrane by cocaine are also interesting. The first 

 observations of this kind date from the year 1888 (Lennox 

 Browne, Gremt). Kiesow (1894) observed that if the nasal 

 mucous membrane is painted high up with cocaine, olfactory 

 sensibility decreases very much, and entirely disappears to certain 

 smells. Goldzweig obtained similar results. Zwaardemaker, 

 however, made the first systematic investigation on the toxic 

 action of cocaine. He found that sensibility was unaltered to 

 some odours and weakened to others, but the results did not 

 conform with his classification. He further observed that the 



