1. The printer's proof of the paper entitled "Oxyhemoglobin Dissociation Curve in the Blood of Lungfish" was received,
corrected and returned to the American Journal of Physiology. It is expected that this paper should appear in print within
four to six months.
2. It was found that although it was possible with the equipment we had to measure oxygen consumption of the living fish when
the aquarium were full of water, it proved impractical when the oxygen consumption was markedly lowered by aestivation and
the volume of air in the system was markedly increased. Therefore, this attempt has been abandoned. The measurement was not
vital to the success of our project, but would have provided interesting observations.
3. A very exciting lead has been achieved in the demonstration of an active principle in the brain of the aesetivating lungfish
a) Dr. Dalton Jenkins of the University of Colorado has established extraction techniques, based on the work of Axelrod and
others, for the extraction of hormones from the mid-brain of the lungfish. It is estimated that such a principle will most
likely by polypeptide, but this is not known.
b) As reported we had four large lungfish in our aquarium. Two of these were forced into aestivation and in the third week
of aestivation attempt was made to kill the fish without a struggle and to extract the brain immediately.
c) Fish A in this series was about a two pound fish. He was found encysted and is a state of typical aestivation in the mud
in the aquarium. Attempt was made to kill him rapidly but this was difficult with the use of the rib shears which we attempted
to use on this occasion. So that this fish struggled for a considerable degree before we were able to severe his head from
the body. Extracts of the brain were prepared and injected intervenously into a white rat. The CO2 production was measured
and there was no observable significant decrease in the CO2 production during the next 24 hrs nor was there a fall in the
d) Fish B in this series weighed approximately two and one-half to three pounds and was found in the third week of aestivation
to be well encysted and apparently in typical aestivation. On disturbing him he began become active rapidly but we were able
to transfer him to a large board and with a meat cleaver severed his head from the body in a single stroke. Thus, there was
much less struggling with Fish B than with the previous one. Extracts were prepared from his brain which was dissected out
immediately. On the following day these extracts were injected intervenously into a white rat. This rat showed a significant
fall for a period of several hours in the production of CO2 as compared to control values. Thus, we have a strong suggestion
that we are now on the rack of an active agent which can supress metabolism originating in the lungfish brain.
4. It is remarkable how rapidly the aestivating lungfish recovers his capacities for flight or fight. When the hole is first
opened the fish appears to be extremely lethargic and in a state of sombulance. On disturbing the fish, however, he appears
to be able to wake up extremely rapidly, and make attempts to bite or escape. It was not expected that the fish would react
in this fashion.
5. On the basis of our proposed focus of this study onto hormones originating from the brain a request was made of our African
agent to find some naturally aestivating lungfish in Uganda, to kill them in the field, extract their brains, process it in
acetone, and send the brains only, to us. On Dec. 28th a package containing 7 brains was received. These brains had been in
transit for 5 days. They were extracted the afternoon of the day they arrived and injected into two mice the following day.
One extract was taken from all of the fore-brains, the other the mid and hind-brains. Neither of the two test rats showed
a depression in their oxygen consumption or CO2 output (our oxygen consumption apparatus has at last arrived and is in commission.)
This was disappointing, but since we did interpret this finding until this information has been received. A delay of 5-7 days
may, and indeed probably does, result in degradation of activity in the brain.
6. At the present time the two remaining large fish have been in aestivation for periods of 5 weeks and 3 weeks respectively
and next week it is planned to move both fish from the mud rapidly chop off the head, dissect the brain and perform the extracts.
The testing of these extracts on rate is planned for January 22nd.
7. With the experience behind us, as mentioned above, we wish to pursue further obtaining of brain material from naturally
aestivating fish in Uganda. There may be inherent difficulties in this procedure, however, due to inability to kill the fish
rapidly, sturgging of the fish under field conditions, the deteriation of the brain in hot weather following death and before
extraction, and the several days it takes in transit from Uganda to Denver. Therefore, we wish to continue to import a few
large fish and to force aestivation ourselves under controlled laboratory conditions.
We are very encouraged by these results and look forward with great impatience to our next studies.