1905. | Substances indirectly Related to Adrenalin. 503 
ONO bn AN 
‘ AAA ay AANA, 
WAN al : 

Fig. 4.—Rabbit, 2°56 kilogrammes. Carotid B. P. Vagi divided. Urethane. 0°005 
gramme piperidino-acetylcatechol as hydrochloride. Zero pressure 30 mm. below signal 
line. Time = seconds. 
The following deductions are made provisionally, until further experimental 
evidence is available :— | 
(i) It appears that the catechol nucleus is essential for the production of 
physiologically active substances of the type of adrenalin. 
(ii) It is of importance that the hydrogen atoms of both hydroxyl groups 
in the catechol nucleus be unsubstituted. 
(ii) An alkyl group of low molecular weight (¢.g., methyl, ethyl) attached 
to the nitrogen tends to produce a much more active substance than when an 
aromatic group is attached, whilst derivatives of piperidine, heptylamine, and 
benzylamine occupy an intermediate position. 
HO 
(iv) The reduction of ketonic bases of the type HOC >.0—CH.R aehere 
O 
R is a simple aliphatic group, results in the production of bases with 
enormously increased physiological activity. 
(v) In the substances examined there appears to be a connection between 
chemical instability and physiological activity, and vice versd. 
In conclusion I wish to acknowledge my indebtedness to the Research 
Fund Committee of the Chemical Society for a grant which has partly 
defrayed the expenses of the work described in this and the preceding paper. 
REFERENCES. 
(1) Knorr, ‘Chem. Berichte,’ vol. 22, p. 2088, 1889. 
(2) Miithlmann, ‘ Deutsch. med. Wochenschrift,’ No. 26, 1896. 
(3) Hans Meyer, International Physiological Congress, Brussels, 1904. 
(4) Dziergowski, ‘Journ. Russian Chem. Soc.,’ vol. 25, p. 154. 
(5) Tunnicliffe, ‘Centralblatt. f. Physiologie,’ vol. 10, p. 777, 1897; Moore, ‘Jour 
Physiol.,’ vol. 22, p. 273, 1897. 
