INFLUENCE OF GLAMU \.\K I-.X I K \t PS. .^7 



unwarranted since the presence of a permanent \-acuolar nu-in- 

 hrane is so extremely doubtful. Also it mu>t In- noted tliat 

 pituitary substance appears to produce an even greater quickening 

 of the pulse rate, while in higher animals it has no effect whatex er 

 on contractile tissues. Degen (6) it will be remembered claims 

 that the acceleration activated by currents of oxygen is merely a 

 compensation for the increased output of carbon dioxide. A 

 similar explanation seems most plausible for the phenomena 

 produced by the glandular extracts. 



Cannon (25) found that inhibition of a strip of intestinal 

 muscle was produced by adrenalin solution as weak as one in 

 tw r enty mill ons, and Janeway and Park observed inhibition of a 

 strip of coronary artery of the sheep with a solution of one in 

 fifty millions. Takayasu using hemisine, a salt of adrenalin, 

 noted that a solution of two in a million seemed to be the threshold 

 strength for inhibition of the sartorious muscle of the frog. In 

 1917 Barbour and Spaeth (2) in studying the pharmacological 

 action in single cells found that epinephrin, the active principle 

 of the suprarenal capsule produced contraction of the melano- 

 phores of Fundulus heteroclitus in all concentrations tested up to 

 one in fifty million. When one considers the far-reaching effects 

 of the various autacoid principles on highly differentiated or- 

 ganisms, it is not improbable that the stimulation of a one-celled 

 organism should be immediately productive of increased metabol- 

 ism, in compensation for which the contractile vacuoles must 

 become more active in their excretion of waste. The duration 

 of the heightened metabolism will be determined to a certain 

 extent by the concentration of the solution and the neutralizing 

 effect of the digestive fluid. The autacoid principle of adrenalin 

 is believed to be speedily rendered inactive by digestive ferments. 

 To confirm this hypothesis one should find that an increased 

 pulse frequency always occurs with increased division rate. 

 The converse would not necessarily be true, since the metabolic 

 effects might be too temporary to effect the division rate. Sell um- 

 way (26) noted that under the stimulation of thyroid extract a 

 rapid pulse rate was coincident with a rapid division rate. 

 Much work remains to be done to confirm this hypothesis. 

 Other glandular extracts should be used and individuals in 



