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The Cell - The Hidden Kingdom (Part 3/6)

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He was the most famous man of Holland and royalty would visit him at his home. The Russian Czar, Peter the Great, and Anne, the new Queen of England couldn't resist a peep through his amazing viewing machine. But van Leeuwenhoek didn't rest on his laurels. He decided to turn his microscope on himself and stepped even further into the hidden kingdom. He scraped the gunk off his teeth and found a whole new family of animalcules. Now, we know them as bacterial plaque, the cause of tooth decay. And in a drop of his own blood he was astonished to see tiny red round things floating around. He described them as globules. We call them red blood cells. He didn't dare tell Queen Anne about his secretive research on human sperm. He used his own semen, acquired, he was keen to stress, not by sinfully defiling himself, but as a natural by-product of conjugal coitus. To be honest, I can't make that same claim. Now it's embarrassing enough talking about this in the twenty-first century. Imagine what it was like in the seventeenth. But you know, there they are - tiny little Adams swimming along - they look kind of like tadpoles. In his own semen, van Leeuwenhoek would have seen the same thing: thousands of tiny little animalcules powering along with whiplash-like tails. He was the very first person to see a human sperm. Another great discovery.

Van Leeuwenhoek had made the earliest link between the microscopic wriggling creatures and the creation of new life. Modern scientists are familiar with the idea that each sperm is an individual cell. And at the moment of fertilisation, the sperm combines with a much bigger cell - the egg. This fusion of cells is the starting point for a new life. But van Leeuwenhoek had no idea of all of this, trapped in a seventeenth century mindset. He believed that the sperm contained a tiny man that once inside the womb, grew into a baby. He never saw him, but others drew fantastical pictures, like this one. The imagination of the microscope pioneers had run beyond their technology.

It's easy to forget where scientists like van Leeuwenhoek and Hook were coming from. The creation of new life was still very mysterious at this time. Many philosophers believed that life originated by spontaneous generation - the idea that creatures could somehow spring forth from inanimate matter. So crocodiles came from rotting logs and bumblebees came from the carcasses of bulls. Now, this stuff sounds completely nuts to our modern ears, but it's an idea that lasted a surprisingly long time.

Spontaneous generation was to prove a persistent obstacle to the advance of cell biology. And it wasn't just a crazy fringe idea: mainstream scientists lapped it up. Take Jean-Baptiste van Helmont, a seventeenth century Flemish aristocrat who did important early work on the chemistry of gases. But van Hellont also wanted to prove that mice arose spontaneously from sweat and grains of wheat. And this is his protocol for making a mouse. If a foul shirt be pressed within the mouth of a vessel wherein wheat is, within a few days (to wit, 21) a ferment being drawn from the shirt and changed by the odour of the grain, the wheat transchangeth into mice. As they say, take nobody's word for it. Here is our vessel and here is some wheat. And here is the crucial extra ingredient - my stinky shirt. And here's one I prepared earlier, to wit, twenty-one days earlier. So let's see if we've made any mice. Well, what a surprise: there are no mice. Now we're not a hundred per cent sure that van Helmont ever actually did this experiment just like I've done. But if he did, then the only sensible explanation is that the mice snuck in to have a bit of a snack. Mice have a habit of doing that. But whatever the truth is, van Helmont believed enough that he actually wrote the protocol down.

Thanks to van Helmont, spontaneous generation was the received wisdom of the day. Because of this, nobody made the connection between what Robert Hook and Antoni van Leeuwenhoek had seen down their microscopes and the origin of life. No one yet suspected that the new discoveries revealed by the microscopes - the strange and wonderful animalcules and globules - were essentially the same thing, and that all life was made of them. For over a hundred years the study of cells was trapped in medieval thinking. It would need pioneers, with the vision and the technology to dive deeper into the world of the cell, before minds could be opened.

The Royal Botanic Gardens, Kew, the early nineteenth century. The deadlock is coming to an end, the science of cell biology is about to be revitalised. And in order to understand how that happened, we need to return to plants. Since Robert Hook's work with cork, botanists had been eagerly tearing up plants to study their anatomy. And what they'd slowly discovered was that plants had some kind of a structure that was made of cells. Every plant they looked at had them: these cells were turning out to be much more prevalent than anyone had realised. But what did they do? What were they for?

A Scottish botanist, Robert Brown, decided to peer into the heart of the plant cell, and there he'd reveal something as important as the discovery of the cell itself. Brown had been the ship's naturalist on an expedition to Australia. He was no slouch, and he returned to Britain in 1805 with over 3000 exotic species, including previously undiscovered orchids. He studied the collection for many years. Now, the orchid was a lucky choice as it happened, because it has cells which are larger than other plants. If it weren't for this, it's unlikely that Brown would have discovered what he did. Now, I'm going to try and see what was so important, using Brown's own microscope.

Hi, David. So this is the actual microscope. This is Robert Brown's microscope from the Linnean Society of London, and it was the one that he used to bring to Kew when he was working on our living collections. And so this is actually where he did this work. Not in this exact spot, but here at Kew, which has been a major collection of plants for over 250 years. And why was he looking specifically at orchids? Well, he was interested in their sex life, basically. And so he was interested to look at pollen grains, and how they actually got to the eggs. And so he was investigating this through this microscope, and so he would get pieces of the flowers, get the pollen out, but he was also interested in the other parts of the plants as well. And so he would mount them on something a bit like this, and under this single lens. Can I have a look? Yes, of course. Can I move this - it looks very fragile. I'd rather you didn't move it. This instrument is a travelling microscope which - he used to come in a hansom cab and this thing was all folded up in a box. And with great difficulty we've put it back together again, and it is a very delicate one now. Brown noticed a distinctive shape within each cell: it was a turning point in science. He called it "the nucleus". Wow, so you really can see every cell, so it's like a - I can see a sort of honeycomb structure, and in many of the cells there's a very solid dark blob in the middle, which I presume is the nucleus. Yes, the point that Robert Brown made was that each cell actually had a nucleus - that was his pioneering discovery. Other people had said they'd seen it, but he was the first to describe it properly, give it a name, "the nucleus", and show how ubiquitous it was. And after he'd seen the nucleus for the first time, what was his interpretation of what he was looking at?

Video Details

Duration: 10 minutes and 10 seconds
Country: United Kingdom
Language: English
Producer: BBC Four
Views: 2,967
Posted by: vallisso on Oct 28, 2009

Episode 1 of 3

Dr Adam Rutherford introduces a new three-part series that tells the extraordinary story of the scientific quest to discover the secrets of the cell and of life itself. Every living thing is made of cells, microscopic building blocks of almost unimaginable power and complexity.

The first part explores how centuries of scientific and religious dogma were overturned by the earliest discoveries of the existence of cells, and how scientists came to realise that there was, literally, more to life than meets the eye.

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