The New Student's Reference Work/Protoplasm

Protoplasm (prō′tō̇-plaz’m), the living substance in animals and plants. Huxley called it the “physical basis of life.” It is the only substance endowed with life. It is very similar in animals and plants, and within it all living activities take place. It is a jelly-like, colorless substance, appearing finely granular under the microscope. It is composed of two parts: one more solid, which stains deeply with dyes (chromatin), and a fluid part (achromatin), which stains very faintly or not at all. The discovery of protoplasm and the gradual appreciation of the part it plays in the living world were among the greatest scientific advancements of the nineteenth century. In 1835 Dujardin, a French naturalist, was studying the simplest animals (Protozoa) under the microscope. He observed that their bodies were composed of a sort of transparent jelly, that moved and contracted and showed evidences of being alive. This soft, jelly-like substance he called Sarcode, and described it as living matter endowed with life. In 1846 Hugo von Mohl, a botanist, called attention to the viscid contents of plant-cells, for which he proposed the name protoplasm. This name had been used in 1840 by Purkinje for animal substance, but Von Mohl first brought it into general use. Presently naturalists began to suspect that the sarcode of the zoologists and the protoplasm of the botanists are essentially identical in nature. This was definitely maintained by Cohn in 1850. In 1860 Max Schultze placed the matter on a secure basis, and applied the term protoplasm to all living substance, either animal or vegetable. This led to what is known as the protoplasm-theory, which absorbed the cell-theory of Schleiden and Schwann. By Max Schultze the cell was defined as a mass of protoplasm surrounding a nucleus. Although protoplasm is so similar in appearance and reactions in all living beings, nevertheless, there must be unperceived differences — possibly not of kind but of degree of modification. See Cell-Doctrine.