Sachs, Julius von

German botanist 1832-1897

Julius von Sachs was born October 2, 1832, in what is now Poland. Although his family was very poor, his brilliance and constant hard work helped him become in his day the foremost authority on the new science of plant physiology. He was made a member of many scientific societies and academies, and was awarded a grant of nobility that allowed him to use "von" before his name. Sachs published several books that became the definitive plant physiology references for many years. His Lehrbuch der Botanik (Textbook of Botany) went through many editions and is still read today.

Sachs's main scientific contributions to plant science came with his early research in the mid-1800s. He enjoyed lab research more than attending lectures in school and he worked with incredible energy and determination. Throughout his career, Sachs strove to find general principles and large concepts involved in botany, rather than focus on smaller, more specific questions. He used microscopic and chemical techniques to study three main areas of plant physiology: carbon use in plants, the mineral requirements of plants, and the effect of temperature on plants. This work laid the foundation for the study of plant physiology among his successors.

In examining the fate of carbon in plants, Sachs used an iodine test to show that carbon was first accumulated as starch in the leaves of plants. He also demonstrated that this accumulation occurred in the chloroplasts and that chlorophyll, light, and carbon dioxide were necessary for carbon fixation. Sachs also observed the way in which the carbon in starch was converted into different compounds in the plant, such as oils, sugars, and proteins. He was one of the first researchers to believe that enzymes did essential work in these metabolic conversions.

Sachs developed a method to culture plants in water instead of soil, which allowed him to experiment with the nutrient content of the water he gave the plants. He used this technique to demonstrate that plants can grow with just water, the right nutrients, and sunlight. Many other scientists believed at first that he must have faked his results—they were certain that soil was necessary for plant growth. Later, of course, Sachs's pioneering research led to the development of hydroponics and the agricultural fertilizer industry.

Sachs's examination of the effects of temperature on plants showed that plants have minimum, maximum, and optimum temperatures at which they grow. These ideas became important later in the study of ecology.

As one of the founders of the modern study of plant physiology, Sachs developed new techniques and scientific instruments, and he helped make plant physiology into a scientific discipline with its own methods and laws. His great authority occasionally led him to be unfair in disagreeing with other scientists (including Charles Darwin) and just his disapproval of an idea could delay research into it. Despite this, Sachs made very important advances in the plant sciences and he was very well respected when he died in Germany on May 29, 1897.