The Cycle of Life:
An History of Experimental Ecology

Sterling Memorial
Kline Sciences
Medical Historical
Exhibit Map

William Henry Brewer, 1826-1910

Norton's student, William Henry Brewer, would take Norton’s lessons into forestry in the late-nineteenth century. Like Norton, Brewer migrated between the family’s agricultural pursuits and their extensive aristocratic society. Brewer had many connections in the scientific community, with whom he shared his growing collections of mosses and minerals. [MOSSES] With the intent of pursuing a scientific career, he first studied chemistry, botany and geology at Ithaca Academy and in 1848 entered the Yale Scientific Laboratory where he took Benjamin Silliman Jr’s courses in chemistry and Norton’s in agricultural chemistry. With his Yale credentials and the support of his personal and scientific network, Brewer taught chemistry at Ithaca Academy between 1850-1851, and at a venture Agricultural Institute in Western N.Y. (His diaries from this period reveal that he enjoyed a number of picnics organized by the women of the school [swing], rare visits by his friends, but first and foremost his trip to Niagara Falls.) In 1852 he received a Ph.D. from the Yale Laboratory and secured a position teaching at physiology, natural philosophy, and agricultural chemistry at Ovid Academy in N.Y. These teaching positions failed, however, to satisfy Brewer.

Brewer never missed the forests for the trees—each played essential part of his psyche and would do so throughout his long life. In 1853, when contemplating the pros and cons of a European apprenticeship, he took a long solitary walk in the woods, set himself down under a tree and “as was his habit fell in dreamy reveries.” “The wind was high, and played among the treetops, hurrying past me, at every blast clouds of leaves, dropping them to their annual grave. How like us mortals. They rustle among the branches, then fall, and soon mingle with the soil, WE flourish for a time, rustle among the branches of society, then pass away to mingle with mother earth, to be soon forgotten . . . .” Brewer’s poetic vision represents the natural theological view that his and Norton’s generation of agricultural scientists, codified into their laboratory investigations.

Brewer finally took the insistent advice of the Sillimans and his close friends who bombarded him with a steady stream of enticing and cajoling letters from various European cities, and in 1854 sailed to Germany. He had calculated that his planned two-year investment would provide him the credentials that he needed to secure a professorship. He studied chemistry first with Bunsen’s excellent laboratory at Heidelberg and later with Liebig much poorer facility at Giessen. Bunsen’s chemical lectures bolstered the holistic vision Brewer had developed in the U.S. From Bunsen’s lecture on “Air,” for example, Brewer learned that living organisms played an important role in maintaining the circulation of matter in nature. In a holistic system that united the animal, plant and geological realms, Bunsen taught that “The oxygen used up during the decomposition of organic matter, during animal respiration, and through absorption by rocks, is recompensed for the animal world, by plants which decompose the CO2 given off from volcanoes.” This was not merely a lesson in theory; with Bunsen, Brewer conducted extensive analyses of organic matter to investigate the role plants played at the juncture of the inorganic and organic realms.

In 1869, Brewer drew on the cycle of life to explain the natural history and recommend the proper management of pastures and meadows—for him two agriculturally significant formations. Here he tried to understand why old pastures that had not been disturbed by the plow for many years were vastly superior to those that were made recently. While climate might determine the characteristics of the pastures, science and agriculture pointed, Brewer wrote, to another important element—the role of human beings in managing the soil. His holistic view stands out in his discussion of proper soil management. If the owner of the pasture wages war against the weeds and encourages more desirable species of grasses, the cattle will eat off the herbage and leave their droppings on the surface. Much of the foliage also dies off each year mingling with the mere surface soils and slowly but surely the vegetable matter increases there. The annual crop is drawn largely from the air, and that which is left on the ground does not go back to its original elements quickly, and thus it is that the vegetable matter increases, especially at the surface. The plants also help to bring the mineral elements in the soil into the cycle by making them soluble, and after the plants die and decay they make them available to future growths.

To justify his evaluation of the importance of pastures in agriculture, Brewer turned not to the Germans with whom he had studied, but to the authority of the French agricultural and organic chemist Jean Baptiste Boussingault. Brewer agreed with Boussingault that the whole object in the best systems of animal husbandry, is to make the earth produce the largest amount of organic matter in a given time. This was an holistic approach based on the recycling of “a heap of dung”—a resource so important in Brewer’s opinion, that he thought it determined the great phases of human progress and decline through history. It explained, for example, the differences between the American North and South. Moreover, it was an essential factor in creating “permanent pastures” and beautifying the landscape, in the furnishing of food for the present generation, and also the promise of permanent wealth and prosperity of the future.

In 1904, in his last lectures to the Yale forestry school that he had helped to found, Brewer discussed the topic of forest physiography, bringing together the cycle of life with physical geography. Just as he thought pastures could be made by “art” so could forests. And, since, for him, the trees are the natural expression of the soil, he approached the subject in the same way. But where in 1869, he could resort to chemical laws to describe the cycle of nutrients in nature, after the 1870s and the work of several agricultural chemists who showed the biological nature of decomposition and soil processes such as nitrification and ammoniafication, he now described the cycle biologically. At the end of his lecture—which coincided with the end of his career, Brewer concluded by looking forward. The forests, he said, have introduced us to another field too wild to discuss [in his lecture] but currently under investigation—that is, forest ecology. Ecology, he explained, is the study of organisms and their relationship to each other, and their relationship to the soil. It is to here—to ecology—that the numerous sciences related to the concept of the cycle of life lead. But that is a subject for future work.

John Pitkin Norton, 1822-1852

William Henry Brewer, 1826-1910
Lloyd Ackert
Whitney Humanities Center
Yale University
53 Wall Street
P.O. Box 208298
New Haven, CT 06520-8298
Office: (203).432.3112

The Exhibit is located at Manuscripts and Archives, in the lobby of the Library Lecture Hall.

Manuscripts and Archives
Sterling Memorial Library
130 Wall Street
New Haven, CT 06520-8240

Contact information.