Cartilage

Cartilage or gristle is present in many parts of the body. It is supplementary to bones, and in many situations it takes the place of bone. It is much more abundant in a young animal than in an adult, for much of the cartilage present in the young animal is replaced by bone during the period of growth; but in many places cartilage persists throughout life. Cartilage is nourished by lymph. Neither blood-vessels nor nerves have been found in the actual substance of cartilage, though blood vessels are present in the clefts in the larger pieces. It is elastic, but is not hard like bone. It is less yielding and pliable than tendons and ligaments, though it is cut more easily with a knife. Cartilage is covered with a fibrous membrane called perichondrium, the only exception is articular cartilage, which has a covering only on its margins.

The founder of virology. (страница 133)

Dmitry losiphovitch Ivanovsky, a prominent Russian scientist, was born in 1864. in 1888 he graduated from Petersburg University and began to study the physic loge of plants and microbiology.

When D.I. Ivanovsky was investigating the tobacco mosaic disease (мозаичная болезнь табака) he was able to come to the conclusion that this disease occurred due to a microscopic agent, many time smaller than bacteria.

To prove this phenomenon D.I. Ivanovsky had to make many experiments on various plants. He had to pass the juice of the smallest bacteria. At that time everybody considered that bacteria were the smallest living organisms. But when D.I. Ivanovsky had completed to pass the juice through a fine filter, he was able to come to the conclusion that the living organisms smaller than bacteria existed in the environment, because when he introduced the filtrate of the diseased plants to healthy ones they became infected.

Before D.I. Ivanovsky nobody had been able to prove the existence of viruses. Dmitry Iosipovithc Ivanovskiy was the first scientist who was able to establish the new branch of microbiology – virology.

The Discovery of Cholera Bacterium (стр.140)

In 1883 Koch went to Egypt to study cholera. At that time there was a widespread epidemic of cholera in Egypt.

Nobody knew the origin of this disease, there were not any protective measures against it.

The disease spread very rapidly from one place to another and thousands of healthy people died. But sometimes some people who were in a constant contact with the disease person did not catch cholera.

As soon as Koch came to Alexandra he and his two assistants Gaffcky and Fisher began their investigations. In the blood, kidneys, spleen, liver and lungs of the people who died of cholera Koch found many microorganisms but all of them were not the agents of cholera. However in the walls of the intestines and in stools Koch always found a microorganism which looked like a comma. Many times Koch tried to grow this bacterium on gelatin but he failed to do it. Many times Koch inoculated (прививал) this bacterium to the experimental animals, but none became ill with cholera. As the epidemic of cholera became less in Egypt, Koch went to India to continue his investigations there. In Kalcutta Koch often walked along its muddy water on the ground near a small house.

Koch looked into that water and he thought he saw there those “commas”. He tool some of this water, analysed it under the microscope many times and found there the same bacteria which he had so many times revealed in the people with cholera. Koch also established that animals could not catch this disease.

The source of the disease was the water, which people drank.