110 
and the CH;COO residue is feat The Hales HOHE: ‘Sigs be 
the contrary, which have free partial valencies, smell strongly. $ 
Stands the list of odoriferous substances, which Durrans’) published. In the comp 
ation the most important compounds which are characterised by their smell — aliphatic ny 
and aromatic hydrocarbons and aliphatic alcohols were placed in classes, with the i? 
elements carbon, hydrogen or oxygen noted. The odour-power was seldom mentioned; a 
the kind of smell very indefinitely described, e. g., n-octane, weak ethereal; n-nonane, - 
mild, sweet; p-ethyl-butylbenzene, weak, like carrots. a 
An apparatus for carrying out smell measurements, constructed a few years ago . 
by M. Fournie, is recommended in a French periodical*). The olfactometer consists — 
of two test-tubes, one of which can be pushed into the other; one is pierced with a - a 
row of vertical holes, the other with a row of holes of a spiral form. By twisting the y 
glasses—-in the interspace of which the odorous body is placed—the various holes — 
can be open or closed at will. Since a clearly understandable description is not at hale 
we must content ourselves with this information. 
Under the title “On the Bees’ Sense of Smell, and its Significance in Flower-Biology’”’*) q 
K. von Frisch has published his interesting researches in book form. These researches ~ 
were thoroughly discussed by us in the Report of 1919, p. 108. 
Like Frisch®), F. Knoll®) arrived at similar results in his investigations, by which 4 
he wanted to ascertain if it is possible to train insects for recognizing colours. The | A 
experiments showed that with the exceptions of red and green, colours were perceived j 
by bees at a much greater distance than they perceived smells. Bees accustomed to ae 
the yellow helianthemum flowers (yellow rock rose) were only attracted by the colour, a 
and flew just as often also to the yellow flowers of other plants growing near, up to & 
a distance of 1 to 0.5 cm. Then at last, recognising their error, they flew on to the © 
next yellow flower, on which they alighted, in case it might be a Helianthemum. A B | 
contrary example to this was furnished by those bees which collected honey fromthe © 
blue to red-violet flowers of Echium vulgare and at the same time flew to the blue- to ; 
purple-coloured flowers of Delphinium, Cichorium, Campanula, Clematis Viticella, L., Vicia ~ 
dasycarpa, Tenore, and Salwa officinalis, L. They did not take pollen from these flowersie P| 
From these and other investigations it further resulted that the universal honeyed * 
perfume so often mentioned in biological books, plays no part worthy of mention. it 2 
is always a case of the specific odour of the flowers in question, which is only peters 
by the insects in the immediate neighbourhood, and only then attracts them. cts 
In order to completely eliminate the action at a distance of the smell of the ‘owed 
Knoll caused the bees to approach them in a direction perpendicular to a current oh 
air passing over and in contact with the flowers. In other cases the flowers: ‘were. 
surrounded by little glass tubes. All experiments led to the result that a colour ~ 
attraction is possible with certain insects, but that red or green had no influence. a 
Investigation and Valuation of Scent-stuffs for Commercial Purposes: — Attempts fay e. 
often been made with the help of. special apparatus (olfactometer) to estimate f 
intensity of smell as sense stimulant. We have discussed Zwaardemaker’s and Hennin, 
1) Cf. Report 1919, 107. — *) Perfum. Record 11 (1920), 79. — %) La Parfumerie moderne 11 ( f 
— ‘) Jena 1919. Publishing House of G. Fischer. — 5) Cf. Report 1919, 108. —. *) Die Naturwissen: 
1919. No. 24. According to kindly forwarded reprint. ak Meone 
