Notes on scientific research. 129 



with unfailing accuracy amongst the many thousands that surround them entirely by 

 their sense of smell. 



Finally, Rorig discusses the question of the individual smell of animals. The most 

 common odour is probably that of musk. Not only the musk-deer but also the little 

 musk-buck (Neotragus moschatus), a dwarf-antelope of Abyssinian origin whose tear- 

 glands contain the musk-secretion, the musk-ox of Greenland (Oribus moschatus), the 

 American musk-pig (Bicotyles lapiatus) whose musk-glands are close to the anus, the 

 North American musk-rat or ondatra (Fiber zibethicus), the musk-shrew (Myogale 

 pyrenaica) of Northern Spain, the musk-rat (Myogale moschatus) of Southern Europe, 

 and several other species of shrews one and all produce this penetrating scent. To the 

 same category belong the prehensile-foot-jumper of Queensland ((Sypsiprymnodon 

 moschatus), a marsupial shrew and the males of the Australian musk-duck (Biziura 

 lobata). Some insects may also be mentioned under this heading, for instance a 

 a bombycid (Porthesia aurifiua) and the musk-beetle (Aromia moschata). 



Observations on the smelling capacity of dogs. — The question if dogs react on odours 

 which affect human beings was hitherto not investigated from an experimental point 

 of view. An essay by C. Heitzenroeder 1 ) attempts to solve it. 



The external signs of dogs scenting any odour are sniffing movements which 

 become visible when the nervus olfactorius is stimulated. These movements can be 

 graphically registered as breathing sensations by means of a girdle attached to the 

 thorax and ending in a so-called Marey's drum. The current of odour is supplied to 

 the dog by means of a hemispherical funnel into which the animal places its snout. 



Heitzenroeder was able to demonstrate by this means that dogs react on many 

 odours which also affect human beings. On the other hand, some substance whose 

 odour is quite imperceptible to human beings, owing to their being exceedingly diluted, 

 produce lively sniffing movements in dogs, for instance an extremely diluted solution 

 of female dog's urine. 



With the aid of this method, L. Seffrin 2 ) tried to determine the keenness of the 

 dog's scent which we referred to in a former Report. 



Smell and chemical constitution. — We discussed the connection between the con- 

 stitution and odour of organic compounds in our last Report according to a paper by 

 R. Marchand 3 ). The same subject has been recently treated by J. V. Dubsky 4 ). He 

 also refers to the meagerness of our knowledge of the relations between smell and 

 constitution, discusses the various odorophorous groups, and above all things draws 

 attention to the similarity of odour of substances built up in a completely different 

 manner. Besides, the term "odorophorous groups" one comes across other denomina- 

 tions in literature. 



For instance, the term "aromatophorous groups" is sometimes in use, and H. Rupe 

 and K. von Majewski 5 ) introduced the designation "osmophorous groups". Even such 

 terms as "kakosmophorous" (evil-smelling) groups, as for instance — SH in the mere- 

 captanes, — S — in the thioethers, — N:C in the carpylamines, are employed. 



*) fiber das Verhalten des Hundes gegen einige Riechstofe; researches of the Physiological Institute of 

 Giessen. Zeitschr./. Biologie 62 (1913), 491. According to a separate impression kindly placed at our disposal. 

 — 2 ) tfber die kleinsten noch wahrnehmbaren Gerucfismengen beim Hand, researches of the Physiological 

 Institute of the University of Giessen. Zeitschr. f. Biologic 65 (1915), 493. (The author kindly sent us a special 

 impression). Comp. Report October 1915, 70. — 3 ) Deutsche Parf.-Ztg. 1 (1915), 232, 243, 287; Report October 

 1916, 104. — 4 ) Deutsche Parf.-Ztg. 2 (1916), 297, 348. - B ) Berl. Berichte 33 (1900), 3401. 



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