One can impair the health if one does not sleep for along period of time.

3. Cholera ['kɒlərə] and other infectious diseases must be fought against.

The human organism can fight against microorganisms thanks to phagocytes.

VII. 1. Прочтите текст А. 2. Переведите письменно 3-й и 6-й абзацы. 3. Найдите: а) неопределенно-личные обороты и переведите их; б) модальные глаголы и укажите, с какими инфинитивами они употребляются. 4. Выпишите и переведите слова с суффиксами -th, -ment, -ive, -ar, -able. 5. Задайте по одному вопросу к каждому абзацу текста так, чтобы охватить содержание всего абзаца. 6. Выпишите английские эквиваленты следующих словосочетаний:

Увеличивается по размеру до определенного предела; 2) в таком случае; 3) большинство микроорганизмов; 4) из-за (вследствие) уплотнений; 5) прийти к выводу.

Text A. Microorganisms

All the existing microorganisms can be divided into two main groups - aerobic and anaerobic. Aerobic microorganisms must have atmospheric free oxygen for their life and growth. However one knows that free oxygen is not favourable for the development of anaerobic microorganisms.

Bacteria vary in shape and according to this feature they are divided into some groups. Spherical bacteria have been called cocci. They are also subdivided into several groups. Rod-shaped (палочковидные) bacteria are called bacilli.

When bacteria multiply they divide. The growing organism increases in size up to a certain limit and in due time divides. The process of division depends on the conditions of the environment.

Any minute [mai'nju:t] (мельчайший) virulent microorganisms may invade the human body. But due to the local protective agents of the human organism they are destroyed. In this case no disease occurs.

However the local protective agents of the human organism are not always able to destroy completely the invading microorganisms. It is known that in such a case a local or general infection may occur.

Most of the microorganisms produce diseases when they enter the tissue and destroy it. If one examines under the microscope the alveoli of the lung of the man with lobar pneumonia, a great number of pneumococci can be revealed. While the disease persists the lung may be considerably impaired because of the consolidations which may develop in it.

But the human organism can fight against the microorganisms which have passed its first protective barriers, i.e. skin and mucous membranes.

The prominent Russian scientist I. I. Mechnikov had made many investigations before he was able to come to the conclusion that leucocytes could catch and destroy certain microbes. I. I. Mechnikov called them phagocytes or microbe cell destroyers.

CLASS ASSIGNMENTS

VIII. Form new words using the given suffixes. Translate the words:

-ence, -ance: occur, persist, exist, depend, enter, clear, appear; -ment: impair, develop, move, establish, appoint, require; -able: favour, control, vary, depend, value, consider; -sion: invade, divide, conclude, decide, diffuse; -th: deep, grow, wide, strong, long, warm, dead; -ish: thin, fat, long, woman, yellow, thick; -ful: use, hope, pain, harm, rest, thank, help.

IX. Answer the following questions:

What conditions are favourable for the growth and life of both aerobic and anaerobic microbes? 2. According to what are bacteria divided into groups? 3. To what limit do growing organisms increase in size when they multiply? 4. Due to what are minute virulent microorganisms destroyed when they invade the human organism? 5. In what case may local or general infection occur? 6. What can be revealed under the microscope in the alveoli of the lung of the man with lobar pneumonia? 7. Why may the lung be considerably impaired while the disease persists? 8. What barriers do skin and mucous membranes form? 9. What is the role of leucocytes in the human body?

X. Read and retell Text B.

Text B. Robert Koch

Robert Koch is a prominent German bacteriologist, the founder of modern microbiology. He was born in 1843, died in 1910. When Koch became a doctor, he carried on many experiments on mice (мышах) in a small laboratory. In 1882 Koch discovered tuberculosis bacilli. In his report made in the Berlin Physiological Society Koch described in detail the morphology of tuberculosis bacilli and the ways to reveal them. Due to his discovery Koch became known all over the world. In 1884 Koch published his book on cholera. This book included the investigations of his research work carried out during the cholera epidemic in Egypt and India. From the intestines of the men with cholera Koch isolated a small comma-shaped (в виде запятой) bacterium. He determined that these bacteria spread through drinking water. In 1905 Koch got the Nobel Prize for his important scientific discoveries.

LESSON 25

HOME ASSIGNMENTS

I. Прочтите данные предложения, обращая внимание на то, чем заменяются модальные глаголы. Запомните эти заменители-эквиваленты:

A. Не can do this work.	=	He is able to do this work.
He could do this work.	=	He was able to do this work.
		He will be able to do this work.
Б. He may do this work.	=	He is allowed to do this work.
		He will be allowed to do this work.
B. He must do this work.	=	He has to do this work.
		He had to do this work.
		He will have to do this work.