Lesson video

Hello, I'm Mr. Marchant, and thank you for joining me for today's history lesson.

I'll be guiding you through all of our resources today and my top priority is to make sure that by the end of our lesson, you are able to successfully meet our learning objective.

Welcome to today's lesson which is part of our Edexcel unit on Medicine in Britain and our AQA unit on Health and the People.

By the end of today's lesson, you'll be able to evaluate the impact of Germ Theory on explanations for the causes of disease in 19th century Britain.

There are two key words which will help us navigate our way through today's lesson, those are microbe and culture.

A microbe is any living organism which is too small to be seen without a microscope and a culture refers to bacteria grown under laboratory conditions.

Today's lesson will be split into three parts and we'll begin by focusing on 19th century medical knowledge.

The 19th century was a period of considerable scientific progress which helped benefit medicine.

Nevertheless, there were still many medical ideas from earlier periods which continued to be accepted.

Medical knowledge in the 19th century benefited from the increasing popularity and acceptance of the scientific method.

Experimentation and observation were increasingly seen as essential to help develop and test new medical theories.

This process helped ensure that there was evidence which could prove new ideas were correct.

However, many scientists and medical professionals still proved reluctant to change their minds about old ideas which meant that it could take a while for new ideas to be accepted.

Technological improvements also benefited medical knowledge during the 19th century.

For instance, microscopes were improved so that higher levels of magnification could be achieved and clearer images could be produced.

These developments helped scientists to begin spotting most if not all, microbes.

Nevertheless, there were some incorrect medical ideas from previous centuries which continued to be accepted in the 19th century.

In particular, miasma, the idea that ill health was caused by bad air, remained very popular as an explanation for the spread of infectious diseases.

Even during the 1880s, official explanations blamed miasma for an outbreak of typhoid in Wales, as well as for a cholera epidemic in British India.

So let's reflect on everything we've just heard.

I want you to identify one improvement which was made to microscopes during the 19th century.

Pause the video here and press play when you're ready to check your answer.

Okay, well done if your answer included that microscopes were able to achieve higher levels of magnification or that they were able to produce clearer images.

And let's try another question.

What did officials claim was the cause of a typhoid outbreak in Wales in the 1880s? Was it divine punishment, miasma, microbes or poor diets? Pause the video here and press play when you're ready to see the right answer.

Okay, well done to everybody who said the correct answer was b, miasma was used to explain why there was a typhoid outbreak in Wales in the 1880s, despite the idea being incorrect.

And this time, we have a statement on the screen which reads, most 19th century doctors considered it unnecessary to gather evidence to support medical ideas.

But is that statement true or false? Pause the video here and press play when you're ready to see the right answer.

Okay, well done to everybody who said that that statement was false but we need to be able to justify our response.

Why is it that that original statement was incorrect? Pause the video here and press play when you're ready to check your answer.

Okay, well done to everybody who said most doctors supported the scientific method and believed medical ideas should be supported by evidence gained from experimentation and observation.

So we're now in a good position to put all of our knowledge about 19th century medical knowledge into practise.

I want you to study the statements shown on the screen.

Firstly, you should identify whether each statement is true or false.

And secondly, I want you to correct any false statements.

You should provide additional detail to support any of those corrections.

So pause the video here and press play when you're ready to reflect on your responses.

Okay, well done for all of your hard work on that task.

So firstly, I asked you to identify whether each of our statements was true or false.

For our first statement, that changes in technology had no relevance to medicine in the 19th century, you should have said that that was false.

For our second statement, that more medical professionals accepted the scientific method in the 19th century, well, you should have said that was true.

And for our third statement, that miasma was no longer accepted as a medical explanation by the late 19th century, you should have said that that was false.

And so then secondly, I asked you to correct any of the statements which were false and to provide additional detail to support those corrections.

So your answer may have included, changes in technology benefited medical knowledge in the 19th century.

For example, as microscopes achieved higher levels of magnification and produced clearer images, knowledge of microbes was able to improve.

And for the other statement, which you needed to correct, you may have written, miasma was still accepted as a medical explanation by the late 19th century.

For example, a typhoid outbreak in Wales in the 1880s was officially blamed on miasma.

So really well done if your own answers look something like those models which we've just seen.

And so now we can move on to the second part of our lesson where we are going to focus on the development of Germ Theory.

Microbes were first observed in the 17th century.

In the 18th and 19th centuries, theories were developed which tried to explain the role of germs and how they might be related to disease.

The most important of these ideas was Germ Theory.

In the early 19th century, many medical professionals who fought about microbes accepted the theory of spontaneous generation.

Many scientists had observed the presence of microbes on decaying materials when using their microscopes.

Spontaneous generation incorrectly explained this by claiming that microbes were the result of decay.

Similarly, spontaneous generation explained the presence of microbes at sites of disease or illness by claiming that the microbes were the result, not the cause of the disease.

Most people who accepted the theory of spontaneous generation also assumed that all microbes were essentially the same as one another.

So thinking about what we've just heard, what did spontaneous generation claim about microbes? Was it that microbes caused diseases, that microbes were the result of disease, or that microbes were never present when there was a disease? Pause the video here and press play when you're ready to see the right answer.

Okay, well done to everybody who said that the correct answer was b, spontaneous generation incorrectly claimed that microbes appeared as a result of disease.

The biggest challenge to the theory, a spontaneous generation was initially developed by Louis Pasteur, a French scientist.

Pasteur was interested in why certain liquids such as wine or milk, decayed and went off.

Pasteur observed that there was bacteria, a type of microbe which always seemed to be present when these liquids went off and suspected they were responsible for decay.

Pasteur then conducted experiments, which showed that boiling liquids could remove bacteria which was present, that if liquids were kept sealed from air after boiling, bacteria did not reappear and the liquid did not go off.

And if liquids were exposed to the air after boiling, bacteria would reappear and the liquid would eventually go off.

Pasteur's work disproved the theory of spontaneous generation.

Instead, his research which he referred to as Germ Theory, showed that microbes appeared in places they could easily reach and were the real cause of decay.

Pasteur also made his work medically relevant by arguing that bacteria caused some human diseases.

So let's reflect on what we've just heard.

We have a statement which reads, Louis Pasteur's experiments proved spontaneous generation was correct.

Is that statement true or false? Pause the video here and press play when you're ready to see the right answer.

Okay, well done to everybody who said that that statement was false, but we need to be able to justify our response.

So why is it that that original statement was incorrect? Pause video here and press play when you're ready to check your answer.

Okay, well done to everybody who said Pasteur disproved spontaneous generation and showed that microbes appeared in places they could easily reach.

In the 1870s, Pasteur's Germ Theory was developed further by Robert Koch, a German scientist.

Although Pasteur had argued that bacteria caused disease, he was unable to identify the specific types of bacteria which caused particular diseases.

Robert Koch was able to overcome this problem.

In 1876, Koch found a way of staining and reproducing a pure culture of the bacteria he thought was responsible for causing deadly anthrax infections.

Koch then injected mice with the bacteria from his cultures and when the mice became ill and infected with anthrax, it proved that the disease was caused by bacteria.

In later years, Koch used similar methods to identify the bacteria which were responsible for causing two other deadly diseases, cholera and tuberculosis.

Therefore, Koch's work proved that Pasteur's Germ Theory applied to human diseases.

Additionally, Koch proved that microbes differed from one another so that specific microbes were responsible for particular diseases.

So thinking about what we've just heard, why did Robert Koch produce cultures of bacteria? Was it to demonstrate that all bacteria were harmless? To prove bacteria couldn't spontaneously appear? Or to test if they would cause certain diseases? Pause the video here and press play when you're ready to see the right answer.

Okay, well done to everybody who said that the correct answer was c, Robert Koch produced cultures of bacteria to test if they would cause certain diseases.

And let's try one more question.

This time, I want you to write the missing word in the following sentence.

Koch's experiment with, blank, in 1876 proved for the first time that specific bacteria could cause diseases.

So what's the missing word? Pause video here and press play when you're ready to see the right answer.

Okay, well done to everybody who said that the missing word was anthrax.

Koch's experiment with anthrax in 1876 proved for the first time that specific bacteria could cause diseases.

And so now we're ready to put all of our knowledge about the development of Germ Theory into practise.

I want you to explain how the work of Louis Pasteur and Robert Koch improved understanding of the causes of disease.

You should include the following terms as part of your explanation, bacteria, culture and anthrax.

So pause the video here and press play when you're ready to reflect on your response.

Okay, well done for all of your hard work on that task.

So I asked you to explain how the work of Louis Pasteur and Robert Koch improved understanding of the causes of disease.

And your answer may have included, Louis Pasteur and Robert Koch improved understanding of the causes of disease by developing Germ Theory.

Pasteur conducted a series of experiments which disproved the idea of spontaneous generation and showed that microbes like bacteria cause decay.

Building on Pasteur's work, Koch proved that specific microbes were responsible for some common diseases.

Koch achieved this by creating cultures of particular bacteria and using these to reproduce particular diseases like anthrax in animals.

Koch also identified the specific bacteria responsible for causing cholera and tuberculosis.

So really well done if your own response looks something like that model which we've just seen.

And so now we're ready to move on to the third and final part of our lesson for today where we're going to think about reactions to Germ Theory in Britain.

In Britain, the medical community was split for many years between supporters and critics of Germ Theory.

This meant that it took some time for Germ Theory to be accepted by the majority of British scientists and medical professionals.

Pasteur's Germ Theory attracted some early supporters in Britain, the most vocal of these supporters was not a medical professional but a physicist called John Tyndall.

Tyndall's own experiments had revealed the large amounts of microbes found in ordinary air.

Tyndall linked his work to Pasteur's, arguing that dust particles carried microbes in the air which could cause decay and spread disease.

However, a large proportion of doctors initially refused to accept Germ Theory.

For instance, one of Britain's best known doctors, Henry Charlton Bastian, continued to support the theory, a spontaneous generation throughout the 1860s.

In particular, Bastian highlighted the fact that bacteria was found so commonly in the human body and elsewhere, that it was almost impossible that these microbes can be causes of disease.

Therefore, a combination of Pasteur's inability to prove that specific bacteria were responsible for causing particular diseases and Bastian's reputation left many doctors in Britain unwilling to accept Germ Theory.

So let's reflect on what we've just heard.

Who argued that it was almost impossible that these microbes can be causes of disease? Was it Edward Jenner, Henry Charlton Bastian, or John Tyndall? Pause the video here and press play when you're ready to see the right answer.

Okay, well done to everybody who said the correct answer was b, Henry Charlton Bastian, a British doctor, argued that it was almost impossible that microbes could be the causes of disease.

And let's try another question.

Why was Henry Charlton Bastian's opposition to Germ Theory significant in Britain? Pause the video here and press play when you're ready to check your answer.

Okay, well done if you answered something like the following, Bastian influenced many others as he was a very famous doctor at the time.

Therefore, Bastian's opposition encouraged many other medical professionals to doubt that Germ Theory was correct.

Robert Koch's work which identified the specific bacteria responsible for causing anthrax, cholera and tuberculosis had an important impact in Britain.

This work provided evidence to support Pasteur's argument that bacteria could cause human diseases.

John Tyndall began to lecture on Koch's findings in 1876 and Koch's works were translated into English in 1879, allowing many more doctors in Britain to understand his research.

This all meant that a growing number of medical professionals in Britain accepted Germ Theory.

Although some outbreaks of disease were still incorrectly blamed on miasma during the early 1880s, by the end of the 19th century, Germ Theory was accepted by most British doctors.

So thinking about what we've just heard, which statement is accurate? That support for Germ Theory grew stronger after Koch's work was translated? That support for Germ Theory grew weaker after Koch's works were translated? Or that support for Germ Theory remained unchanged after Koch's work was translated? Pause video here and press play when you're ready to see the right answer.

Okay, well done to everybody who said that the correct answer was a, support for Germ Theory grew stronger after Koch's work was translated.

This was largely because Koch's work was able to provide evidence that particular bacteria were responsible for causing specific diseases.

So we're now in a good position to put all of our knowledge about reactions to Germ Theory into practise.

We have a statement which says, "Although it was correct, Germ Theory was not widely accepted in 19th century Britain." How far do you agree? I want you to explain your answer in two paragraphs.

So pause video here and press play when you're ready to reflect on your response.

Okay, well done for all of your effort on that task.

So we had the statement which said, "Although it was correct, Germ Theory was not widely accepted in 19th century Britain." And your answer may have included, to some extent, the statement is correct because many doctors were initially reluctant to accept Germ Theory.

Pasteur argued that microbes like bacteria were responsible for decay and said that they also caused some human diseases.

However, this theory had many critics, including the famous doctor, Henry Shelton Bastian.

Bastian continued to support the idea of spontaneous generation and highlighted Pasteur's lack of proof to show that particular diseases were caused by specific bacteria.

Furthermore, Bastian's fame in Britain encouraged many other doctors not to accept Pasteur's Germ Theory during the 1860s or 1870s.

In fact, even in the 1880s, official explanations for the outbreak of some infectious diseases still blamed miasma rather than microbes.

Nevertheless, the statement does not reflect the widespread acceptance which Germ Theory had gained by the end of the 19th century.

Robert Koch's work was particularly important for this as he successfully identified the specific bacteria responsible for causing anthrax, cholera, and tuberculosis.

This provided evidence to support Pasteur's theory about microbes causing disease.

British doctors were able to learn about Koch's work as John Tyndall provided lectures on the subject and Koch's work was translated into English in 1879.

This finally convinced many doctors to change their minds so that by the end of the 19th century, Germ Theory was accepted by most medical professionals who could now accurately explain the causes of many common diseases.

So really well done if your own response look something like that model which we've just seen.

And so now we've reached the end of today's lesson which puts us in a good position to summarise our learning about new 19th century ideas about the causes of disease and illness.

We've seen that miasma remained a common explanation for disease in the 19th century.

Spontaneous generation suggested that microbes appeared as a result of decay of disease.

Louis Pasteur's Germ Theory disproved spontaneous generation and showed that microbes were responsible for decay.

Robert Koch's work with cultures proved that specific bacteria caused particular diseases like anthrax and cholera.

And Germ Theory was initially unpopular in Britain but was widely accepted by the end of the 19th century, especially after Koch's work was translated into English in 1879.

So really well done for all of your hard work during today's lesson.

It's been a pleasure to help guide you through our resources today and I look forward to seeing you again in future as we continue to think about Medicine in Britain and Health and the People.