 Hey everybody Dr. O here. In this video I'm going to talk about several people but I'm not going to ask you to know them. But we're going to talk about the debate between spontaneous generation and biogenesis. So spontaneous generation was believed until the end of this video I'll explain when it was disproven. But spontaneous generation said that life came from nothing. It came from this vital force or a life force or a vegetative force. Those are all the different terms I've heard used to describe it. The newer theory was this idea of biogenesis was genesis means creation of life. Which means that all living things come from pre-existing living things, right? So we'll look at how this played out over decades before the theory of spontaneous generation was finally disproven and now everyone believes the theory of biogenesis. But let's start back with spontaneous generation because it's interesting. So they didn't know where life was coming from. They didn't know the germ theory of disease. They couldn't see microbes. So at this time like my favorite examples like where that mice and rats actually came from the mud of the Nile River or wasps and beetles actually came out of cow dung. Or my favorite is if you wanted to get bees you would kill a bull and bury it so only its horns were sticking out and then come back. I don't remember how long but come back in a few weeks or a month and saw off the horns and bees would come out. This is where they believe living things came from. Life was coming from nothing. It was materializing because of this vital force. So Francisco Reddy was the first person credited with really taking a stab at defeating this theory. So let me show you his experiment here. So we had a container on the left here just an open container with meat where he actually watched the flies enter it. They were laying their microscopic eggs that couldn't be seen and then maggots were coming. So at this time they believe maggots came from meat. And then he had this some sealed container where as long as the flies couldn't get in there weren't going to be maggots on the meat. And then here we see this gauze or this net like container and you could actually see there were no maggots but you could eat the on the meat but they were forming on the gauze. So the flies were laying the microscopic eggs that were becoming the maggots. This is the first volley in the war against spontaneous generation. But then we have another player. This is John Needham. I don't know pictures of his experiments but he was a firm believer that microbes came came from mutton gravy. He came from what we were growing them at the time. So he used the term vegetative force but you'd also see the vital force and life force. So he had problems with tons of experiments. He did some where he sealed flask but he sealed it with cork that must have been porous enough that the microbes that were getting in. So he was seeing microbial contamination in sealed containers. So he believed that was evidence that the theory of spontaneous generation was still true that nothing could get in but obviously that's not the case. So and he had a lot of problem with other people's experiments. He was just really not willing to give up. He believed like when you did seal a container maybe the vital force or the life force couldn't get in or like if you boiled a container too much you were actually destroying the vital force of the life force. So he I mean he was grasping his straws but John Needham would just not give up on this idea of spontaneous generation. Then we have a couple more players here and you'll recognize one of them but Lazaro Spallanzani he was able to say okay if you're if you have experiments where microbes are clearly getting in through this porous cork I can defeat that. So he would actually seal the ends of glass flask. He would melt the glass and seal them and then there was no nothing getting in. There was no contamination once it had been boiled and there was no growth. So he's credited with saying life only comes from life but people still didn't you know that still didn't believe him. So along comes the last character in this saga and you'll know him. This is Louis Pasteur and his S shaped flask. So so he did hundreds of experiments proving that it wasn't air or a vital force and air that was causing contamination with microbes. It was something in the air. So let me get just a closer view of the flask here. So so a little little history tidbit. He wasn't his idea. A professor Ballard that he worked next to in a cubicle or office whatever. The same person that actually discovered the element bromine. He's the one that came up with this idea of this flask. So what happened here was you take the flask and you boil it to kill off the organisms that are there and also drive out drive out the air that's in it. But then you do not seal the end of the flask. This S shaped flask actually allowed air to enter the flask but microbes couldn't make this trip. You know kind of like if you want an example. It's kind of like how the longer you read through of the mail makes it much less likely to develop your intract infections. So as long as this S shaped flask was was on top of this container. There was no contamination. You can leave these open for indefinite period of time. But as you see in the picture here when you broke that off and now the microbes in the air were quickly and easily able to contaminate this. So this this S shaped flask is the experiment that disproved the theory of spontaneous generation proving the theory of biogenesis. So Louis Pasteur kind of had the last laugh and I have a quote from him. He said never will the doctrine of spontaneous generation recover from the portal blow that this simple experiment has dealt it. Alright so that's the debate over spontaneous generation versus biogenesis and just so I'm crystal clear we we now believe in the theory of biogenesis where life comes from life. All living things come from pre existing living things. Okay. I hope this helps. Have a wonderful day. Be blessed.