tw ) 
We have been in a position to cause the combinations in which 
we agree, to be examined by a third person, Mr. H. Heringa, assistant 
at the laboratory. In order to make a comparison possible, the cases 
meant are put here side by side. 
| Of the proportional numbers in column 4 (Ha) three deviate very 
little from the corresponding values in column 2 (Z) and 3 (Hs), 
viz. terpineol to valerian acid, aethylbisulfide to scatol, guajacol to 
valerian acid (strictly speaking it is only aethylbisulfide to scatol 
that remains within the limits of the probable errors; the others 
are, speaking roughly, in agreement with each other). 
If we connect this with the division into two ordinary groups A 
and B, we are led to single out from the nine standard-groups three 
groups, whose action upon the normal olfactory organ is presumably 
characteristic and in general equal for different persons (at least three 
observers got about the same quantitative proportions, when trying 
these three odours in combinations). 
They are the odours: 
From group A. 
terpineol 
guajacol 
From group B. 
valerian acid 
It is to be recommended for the present to continue the investi¬ 
gation with these three odours, for it has been these three materials, 
chemically sharply defined, which have exercised a quantitatively 
agreeing influence on the sensorial complex of three observers* 
mutually quite independent of each other. Therefore it may be 
assumed that the action of these odours, apart from the accidental 
psychological appreciation, within the limit of the probable errors 
and based upon the physiological organisation, possesses a sharply 
outlined nature and a very definite degree of intensity. 
About the results of the bilateral combination of odours I hope 
I shall be able to offer a communication later on, when the three 
odours, which usually act in the same way, shall have beenimesti- 
gated on this point by more observers. 
