Rhetorical functions in academic writing: Reasons and explanations

There are several factors to be taken into account when studying why some plants become weak or die. One reason is lack of water. Dryness in the soil causes the leaves to wilt, and may give rise to the death of the plant. On the other hand, too much water may result in the leaves drooping, or becoming yellow. While sunshine is necessary for plants, if it is too strong, the soil may be baked and the roots killed. However, if there is no light, the leaves will become pale and the stems thin. Consequently the plant may die.

War, meantime, had broken out between the United States and Mexico. The main cause was a long standing dispute over where the southern boundary of Texas belonged. Americans were saying it lay along the Rio Grande, and the Mexicans were insisting that it belonged along the Nueces River.

Henry Graff, The free and the brave. Rand McNally, 1968.

While this is not the place to discuss the pros and cons of American policy in Southeast Asia, Americans should not have been surprised by Martin Luther King's stand. In opposing what he considered to be an imperialistic adventure and a war of colonial oppression, King was acting in the great tradition of Negro leaders throughout American history. Frederick Douglass, it will be recalled, had denounced the American war against Mexico; his son had ridiculed and protested the American war against Spain. And to a man of Dr. King's historical scholarship, the dangers to the struggle for Negro rights of continued American participation in the Vietnam conflict seemed clear.

First of all, no matter what the proclaimed intentions of the American government might be, American soldiers were fighting against a colored people as they had in the Philippines from 1898 to 1901; and that could only aggravate anti-Negro feeling domestically. Secondly, Negro troops who provided more than eleven percent of the American combat forces in Vietnam and suffered eighteen percent of the casualties might well ask themselves the same question that Private William Simms found unanswerable during the Philippine campaign. In the third place, militarism had always been the arch-enemy of tolerance and progress. After each of America's wars, there had been a reaction of more or less severe hysteria against all progressive movements, including the struggle for Negro equality. And finally (as Dr. King reminded his critics), he had received a Nobel Prize for peace, he was a citizen of the world as well as an American Negro, and he felt himself responsible to work for peace everywhere. From the viewpoint of history, it would seem that Dr. King had no need to apologize at all for his new position.

Robert Goldson, The negro revolution, Macmillan, 1968.

DNA is unique in three respects. First, it is a very large molecule, having a certain outward uniformity of size, rigidity and shape. Despite this uniformity, however, it has infinite internal variety. Its varied nature gives it the complexity required for information-carrying purposes. One can, indeed, think of the molecule as if it had a chemical alphabet somehow grouped into words which the cell can understand and to which it can respond.

The second characteristic of DNA is its capacity to make copies of itself almost endlessly, and with remarkable exactness. The biologist or chemist would say that such a molecule can replicate, or make a carbon copy of itself, time and again with a very small margin of error.

The third characteristic is its ability to transmit information to other parts of the cell. Depending upon the information transmitted, the behavior of the cell reflects this direction. As we shall see, other molecules play the role of messenger, so that DNA exercises its control of the cell in an indirect manner.

William McElroy & Carl Swanson (Eds.), Foundations of biology. Prentice-Hall, 1968.