Foreigners are not allowed to drive in China, and you can see why. The Chinese drive, or cycle, according to laws that are simply not apparent to an uninitiated observer, and I'm thinking not merely of the laws of the Highway Code, I'm thinking of the laws of physics. By the end of our stay in China I had learnt to accept that if you are driving along a two lane road behind another car or truck, and there are two vehicles speeding towards you, one of which is overtaking the other, the immediate response of your driver will be to also pull out and overtake. Somehow, magically, it all works out in the end.

What I could never get used to, however, was this situation: the vehicle in front of you is overtaking the vehicle in front of him, and your driver pulls out and overtakes the overtaking vehicle, just as three other vehicles are coming towards you performing exactly the same manoeuvre. Presumably Sir Isaac Newton has long ago been discredited as a bourgeois capitalist running dog lackey.

Tongling, in turn, made us long wistfully for the cheerful, familiar hominess of Nanjing.

To quote the welcoming brochure for tourists that I found in my bleak hotel bedroom: 'As a new rising industrial mining city, Tongling has already founded a rather scale of non-ferrous metallurgical, chemical, textile, building material, electronics, machinery, iron and steel and coal industries; especially the non-ferrous metallurgical building material and chemical industries, which, with a broad prospect of development, have already made or been on the way of making Tongling the major production centre.'

Tongling was not beautiful. It was a bleak, grey, unwelcoming place, and I made immediate plans to lay down a territorial aftershave marker here.

I took the brochure with me and met Mark and Chris in the hotel restaurant, which was also bleak. We had been pretty open to suggestion as far as food had been concerned in China, and had been prepared, sometimes recklessly prepared, to eat whatever people put in front of us. Much of it had been delicious, much of it less so, and some of it had been rather startling to a Western palate.

The food in the hotel in Tongling fell heavily into the startling category, including, and especially, the Thousand Year Old Eggs. The name is, of course, not meant to be taken literally, but merely as a sort of hint as to how startling they are.

The eggs are lightly boiled in green tea and then buried in a box of mud and straw for three months. In that time the white turns bright green and firm, and the yolk turns very, very dark green indeed and sludgy. The startling thing is that they are then presented to you as a delicacy, whereas if you found them in your cupboard at home you would call in the council.

We struggled a little with the meal, finally gave up and looked through the brochure again, in which I discovered another passage: 'It has been already decided to set up a water reserve to protect Lipotes vexillifer, a kind of precious rare mammal in Yangtze River, which is now regarded as "Panda in water".'

`Have you noticed the beer you're drinking?' Mark asked me.

I looked at the bottle. It was called Baiji Beer. It had a picture of a dolphin on the label, and the Latin name for it, Lipotes vexillifer, printed on the cap.

'I noticed another hotel on the way into town this afternoon,' said Chris. 'I thought, there's a funny coincidence, it's called the Baiji Hotel. Looked a sight better than this dump.'

Even if we'd come to the wrong hotel, we'd clearly come to the right place.

A day passed before, with the aid of Professor Zhou's letter, we were able to find an English-speaking guide and organise a small boat to do what we had come to do: go out on to the Yangtze River and look for baiji dolphins ourselves.

We were by this time two or three days behind the schedule we had originally planned, and had to leave the following morning on a ferry to Wuhan. We had therefore only a few hours in which to try and see one of the rarest aquatic mammals in the world in a river in which it would be hard to see your hand in front of your face.

Our small boat chugged away from a small, crowded wharf and out on to a wide extent of the dirty brown river. We asked Mr Ho, our guide, what he thought our chances of success were.

He shrugged.

`You see there are only two hundred baiji in two thousand kilometres. And the Yangtze is very wide. Not good, I think.'

We chugged along for quite some time, making our way gradually towards the opposite bank, about two kilometres away. The water was shallower there, which meant that there was less boat traffic. The dolphins also tend to keep close to the banks for the same reason, which means they are more likely to get snared in the fishing nets, of which we passed several, hung from bamboo frames extending from the banks. Fish populations are declining in the Yangtze and, with all the noise, the dolphins have greater difficulty in `seeing' the fish that there are. I guessed that a net full of fish might well lure a dolphin into danger.,

We reached a relatively quiet spot near the bank, and the captain turned off the engine.

Mr Ho explained that this was a good place to wait, maybe. Dolphins had been seen there recently. He said that that might be a good thing, or it might not. Either they would be here because they had been recently, or they would not be here because they had been recently. This seemed .comfortably to cover all the options, so we sat quietly to wait.

The vastness of the Yangtze becomes very apparent when you try and keep a careful watch on it. Which bit of it? Where? It stretched endlessly ahead of us, behind us and to one side. There was a breeze blowing, ruffling and chopping up the surface, and after just a few minutes of watching, your eyes begin to wobble. Every momentary black shadow of a dancing wave looks for an instant like what you want it to look like, and I did not even have a good mental picture of what to look for.

`Do you know how long they surface for? I asked Mark.

'Yes...'

'And?

`It isn't good news. The dolphin's melon, or forehead, breaks the surface first, as it blows, then its small dorsal fin comes up, and then it plunges down again.'

`How long does that take?'

`Less than a second.'

`Oh.' I digested this. `I don't think we're going to see one, are we?'

Mark looked depressed. With a sigh he opened a bottle of baiji beer, and took a rather complicated swig at it, so as not to take his eyes off the water.

`Well, we might at least see a finless porpoise,' he said.

`They're not as rare as the dolphins, are they?'

`Well, they're certainly endangered in the Yangtze. There are thought to be about four hundred of them. They're having the same problems here, but you'll also find them in the coastal waters off China and as far west as Pakistan, so they're not in such absolute danger as a species. They can see much better than the baiji, which suggests that they're probably relative newcomers. Look! There's one! Finless porpoise!'

I was just in time to see a black shape fall back in the water and disappear. It was gone.

'Finless porpoise!' Mr Ho called out to us. `You see?

`We saw, thanks!' said Mark.

`How did you know it was a finless porpoise? I asked, quite impressed by this.

`Well, two things, really. First, we could actually see it. It came right up out of the water. Finless porpoises do that. The baiji doesn't.'

'You mean, if you can actually get to see it, it must be a finless porpoise.'

'More or less.'

`What's the other reason?

°Well, it hadn't got a fin.'

An hour drifted by. A couple of hundred yards from us big cargo boats and barges growled up the river. A slick of oil drifted past. Behind us the fish nets fluttered in the wind. I thought to myself that the words 'endangered species' had become a phrase which had lost any vivid meaning. We hear it too often to be able to react to it afresh.