killing him,
how long could we stop his heart?
- The less time the better.
- I know, but what's the maximum?
In his comatose state and
everything slowed down,
no more than 60 seconds.
At top speed, adjusting distance
for degree of miniaturisation,
that sub should get through the heart
in exactly 57 seconds.
That's only three seconds to revive him.
What are the problems involved
in stopping the heart?
Nothing - compared with starting it up again.
We're wasting time. Let's get on with it.
Message to Proteus.
- Cardiac red alert.
- Maintaining maximum speed,
the sub should get through the heart
in 57 seconds.
This will allow us three seconds to spare
in which to revive him.
To minimise the turbulence
we will have to arrest the heart.
Prepare for cardiac shock. Remove the radar.
The Proteus will proceed
to the entrance of the right atrium,
at which point the heart will be stopped -
by electric shock.
57 seconds.
And if it takes longer to get through?
We can't take a second more.
Captain, head in the direction of the flow
and then drift with it.
Well, that looks pretty complicated.
I shall be able to guide you once we're inside.
Ready for cardiac shock.
Cardioscope.
Tracking.
Listen. The heart.
- Yes. It's slowed down a great deal.
- Sounds like heavy artillery.
It lays down quite a barrage.
Over 40 million beats in a year.
And every beat separates a man from eternity.
Stand by.
They're about to stop the heart.
Full power when we enter the valve.
Hit it!
24 seconds left. Including three to revive him.
19 seconds, Doctor.
The semilunar valve
should be on our left any second now.
Stand by to revive.
- There it is.
- Bear to your left.
- Can you see it, Captain?
- Yes. I see it now.
Brace yourselves. There'll be a tremendous
surge when the heart starts up again.
If it does.
Eight seconds left.
Now!
They're in the pulmonary artery.
They'll make up time once they get
through that and reach the pleural cavity.
Respiration post.
- What's his rate, Jack?
- Back to six per minute.
Dammit! I just had them cleaned.
They all lead to the same place:
The lungs.
Dr Michaels,
the channel is getting awfully narrow.
Yes, we're entering a capillary.
Try to stay in the middle.
The wall's transparent.
It's less than one ten-thousandth
of an inch thick. And porous.
Doctor, just think of it.
We're the first ones to actually see it happen.
The living process.
Mind letting me in on
what's going on out there?
It's just a simple exchange, Mr Grant.
Corpuscles releasing carbon dioxide
in return for oxygen
coming through on the other side.
- Don't tell me they're refuelling!
- Oxygenation.
We've known it exists
even though we never saw it.
Like the structure of the atom.
But to actually see
one of the miracles of the universe,
the engineering of the cycle of a breath...
I wouldn't call it a miracle.
Just an interchange of gases.
The end product
of 500 million years of evolution.
You can't believe all that is accidental? That
there isn't a creative intelligence at work?
Well, the creative...
- Mr Grant?
- Yes, skipper?
I'm losing pressure in the flotation tanks.
Check the manual control panel.
It's aft on the starboard side.
The left tank's losing pressure.
There must be a short
in the electrical valve circuit system.
Yeah.
That takes care of the valves. I suppose it
happened because of that electric shock.
- Is there any damage?
- Not to the valve.
But we've lost so much air
we can't make it the rest of the way.
What do you propose to do, Captain?
There's nothing we can do.
We can't continue without full tanks.
- Any reserve air?
- Enough to breathe, but that's all.
Just a few cells away from a vast air chamber,
one of the countless alveoli of the lung,
and we can't get enough air
to fill a microscopic tank!
Maybe we can.
- Skipper, is there a snorkel on this sub?
- Yes, there is.
Could I run a tube through that