833 
In order to confirm this hypothesis it must first of all be ascer- 
tained whether the places mentioned sub B (i.e. the secondary 
chemoreceptors) really exist in the body. 
In this paper we shall endeavour to settle this question with 
regard to cocain. 
As already stated the researches of Brier, Sano, Harcurr and 
Eeeieston, and others had already brought to light that cocain can 
be inactivated by animal tissue. It lay with us to show that this 
inactivation takes place through physical adsorption. 
We had to proceed as follows: 
1. We had to ascertain the action of a cocain solution of known 
strength on a special organ. | 
2. We had to show that the cocain solution became less active 
after the addition of animal tissue. 
3. We had to demonstrate that the cocain was not decomposed 
in the less active mixture, so that all the active cocain could again 
be extracted from the mixture. 
The effect of cocain upon the nervus Ischiadicus of the frog was 
taken as the index for cocain-action. We applied Zorn’s *) method °), 
of which we give a brief description (see: Fig. 1). 
The nerve of a-nerve-muscle preparation is led through a small 
ebonite basin, which is to hold the cocain (and other liquids); on 
either side of the place where the nerve is in contact with the local 
anaesthetic, electrodes can be applied, which communicate with the 
secondary coil of an inductorium. By the aid of Pohl’s commutator 
the nerve can be stimulated alternately by EH’ and KE". First the 
position of the secondary coil is determined (to be read from S) at 
which the muscle can just be stimulated from KE’ as well as from 
E". Subsequently the liquid with the local anaesthetic is put in the 
basin, and after this we investigate how strong the solution must be 
in order to make the muscle after a certain time irresponsive to 
the stimulus from the electrode E’. The stimulus from E” must 
retain its effect upon the muscle to make sure that during the expe- 
riment the excitability of the muscle itself is not diminished. We 
invariably experimented with a gastrocnemius-ischiadicus preparation 
of Rana esculenta. Due care was taken to keep the room-tempera- 
ture constant. We made sure beforehand that the liquids used for 
h Zorn. Beiträge zur Pharmacologie der Mischnarcose. Il. Zeitschr. f. exp. 
Path. und Ther. Bd. 12, p. 529 1913. 
1 Cf W. Storm VAN LEEUWEN. Physiologische waardebepalingen van 
geneesmiddelen. Wolters, Groningen, 1919. 
55” 
