SECTIONAL TRANSACTIONS —I. 363 
corrected. ‘The principal factors are (1) pregnancy and loss of blood at 
the periods, leading to increased demands for iron ; and (2) an iron-poor 
diet which fails to maintain adequate reserves to meet such eventualities. 
Dieto-therapy and the administration of iron-salts rapidly and cheaply 
cause a remarkable improvement in health, with a corresponding gain in 
economic efficiency and resistance to disease. 
Dr. F. J. W. Roucuton.—Recent work on carbon dioxide transport. 
Since 1928 there have been two new developments in the problem of 
carbon dioxide transport by the blood : 
(1) It has been found that the red blood corpuscles (but not the plasma) 
contain large amounts of a powerful enzyme, carbonic anhydrase, which 
catalyses both phases of the reversible reaction, H,CO, = CO, + H,O. 
(2) Small amounts of carbon dioxide have been shown to combine 
directly with the hemoglobin of the blood to form compounds probably 
of a carbamino type, e.g. HbNH, + CO, =HbNHCOOH (hemoglobo- 
carbamic acid), and possibly of some other type as well. The tendency to 
form carbamic compounds is far more marked in the case of reduced 
hzmoglobin than in oxyhemoglobin. 
These two discoveries mean that our previous views require some 
resetting. An attempt will be made to give an up-to-date picture of the 
operations which confront the CO, molecule from the earliest stage, i.e. its 
liberation in the course of metabolism, right up to the final stage, viz. that 
of liberation into the expired air. 
Dr. G. A. MILLikan.—Recent work on the hemoglobins. 
The family of the hemoglobins is becoming daily more diverse. Dif- 
ferent animals may possess hemoglobins with molecular weights ranging 
all the way from 17,000 (Chironomus) to several million (Arenicola). And 
even in the blood of a single animal, there is now evidence that there may 
be two or more hemoglobins differing from each other in iso-electric points 
or in resistivity to denaturation. Recent spectroscopic work shows, more- 
over, that the hemoglobin inside the corpuscle may differ markedly from 
that of laked blood. Finally, kinetic experiments show that there may be 
large differences in the reactive properties of hemoglobin depending upon 
whether it has very recently been oxygenated or reduced. 
Muscle hemoglobin has been shown to possess an oxygen dissociation 
curve of the simple hyperbolic type, interpretable on the classical Hiifner 
theory. For pigments showing the commoner sigmoid curves, new kinetic 
evidence, as well as the older molecular weight data, overwhelmingly favours 
the “ step-by-step ’ intermediate compound hypothesis as against the ‘ all-at- 
once ’ theory. 
AFTERNOON. 
Visit to the Rowett Research Institute. 
Friday, September 7. 
Jomnt Symposium with Section M (Agriculture) on Nutrition in relation 
to disease (10.0) :— 
Dr. J. B. Orr, D.S.O., F.R.S. 
_ Ashort non-technical account is given of the broad principles of nutrition 
in relation to disease which have been established in the Jast twenty-five 
