746 REPORT—1904. 
increased yield of carbonic acid due to activity was claimed or denied by these 
observers strikingly in proportion to the success with which the artificial circula- 
tion had been made to reproduce the normal. A third and large body of evidence 
is supplied by observers like Araki, Geppert, Meyer, and others, who have studied 
the results of muscular contraction with normal circulation, but under conditions 
of deficient oxidation. Anaérobic conditions always appear to diminish the 
amount of carbonic acid expired, while increasing the amount of acid products in 
the tissues, the blood, or the excreta. 
The following letter from Professor Zuntz was read :— 
‘Berlin, August 1, 1904. 
‘Dear Sir,—I put off answering your letter of July 11 till to-day, because I 
was always hoping to be able to arrange to come to the meeting. Now I must, 
however, quite definitely give up all hope of this pleasure. 
‘I should like, however, to take the liberty of making some remarks on the 
questions, which I herewith return. Would you please read at the meeting just 
so many of these remarks as you think a propos ? 
‘In the case of Nos. 1-4 I should like to suggest the following question. Is 
one justified in drawing a hard line between the anabolic and the katabolic pro- 
cesses on theoretical grounds? Would it not be more correct to take Pfliiger’s 
view (“ Ueber die physiologische Verbrennung in den lebenden Organismen,” P/. 
Arch. x.), and regard that process as the normal one, in which every katabolically 
decomposed molecule is at the very moment of decomposition anabolically rege- 
nerated by taking up oxygen and oxidisable groups? In this case one would 
regard the katabolic processes, which render the molecular structure less stable 
and give rise to free affinities, as the factor which inaugurates and makes possible 
normal anabolism. In this connection, however, the fact remains that anabolism 
can also take place later on if an element, such as oxygen, necessary to the 
building up of the molecule, should be wanting at the time that the katabolic 
processes occur. It is, accordingly, a subject for investigationto decide whether 
subsequent regenerative processes occurring in the above manner take place as 
easily as normal assimilation occurring at the same time as the breaking down 
of the molecule, or whether they use up more energy if they occur later. 
‘I have already some experimental data which would tend to show that 
anabolism demands more energy if tt has to take place at a period after the kata- 
bolic processes, but I dare not yet give any definite verdict on the question. 
‘In the case of 5, I should like to lay stress on the fact that the fundamental 
importance of innervation for katabolic processes in muscle is not easy to reconcile 
with the assumption that these processes are much affected by enzymes. Neither 
does the great influence which the tension of a muscle has on oxidation pro- 
cesses in it harmonise with our knowledge of the action of enzymes. In the case 
of 7, you will permit me to refer to my observations on working men and animals 
which, to some extent in contradiction to many less recent results, have proved 
that under normal conditions of nourishment the respiratory quotient remains 
the same for rest and for work; a fact which tends to show that the same foods 
also are oxidised in the same way in both cases. (Compare ‘ Untersuchungen 
iiber den Stoffwechsel des Pferdes,’ Berlin, 1898; ‘Studien zur Physiologie des 
Marsches,’ Berlin, 1901. Pfliiger’s Arch. 83, Heft 10-12. 
‘Part of the above I wrote as Question 8 on the enclosed sheet. 
‘ With sincerest greetings, I am, yours truly, 
‘N. Zunrz. 
Questions referred to in the above Letter. 
Is the anabolic process accompanied by absorption of oxygen? 
Is the anabolic process accompanied by evolution of CO, ? 
Is the katabolic process accompanied by absorption of oxygen? 
Is the katabolic process accompanied by evolution of CO, ? 
. How far is either of these processes the work of an oxidase ? 
Our oo bor 
