botany and zoology, were also progressing during this period: Zenkovsky was one of the first to study the anatomy and physiology of plants, and contributed to the progress of bacteriological investigations. Famintsin also worked at the physiology of plants and explained the influence of light on them, and the phenomena of symbiosis; Timiryazev, a convinced partisan of the mechanical conception of physiological processes and a strict adherent of Darwinism, studied the composition and properties of chlorophyll, and other questions of vegetable life. Zoology and particularly embryology owed much also to Russian students: this new science was founded by Baer, one of the greatest embryologists; but Baer was not prepared to accept the theory of evolution in its phylogenetic sense; and this was done by Kovalevsky and Metchnikov, who contributed to further progress. Kovalevsky made very important investigations concerning the embryogeny of invertebrates (Ascidiae, Amphioxus lanceolatus, Bonellia, Sagitta, etc.), their secretory organs, lymphatic glands, etc. Metchnikov was, with Kovalevsky, one of the founders of the modern embryology of invertebrates: he proved that their embryonic layers develop in a way similar to those of higher organisms, as may be seen in scorpions and other types; he signalized himself moreover by his microbiological studies on intracellular digestion and on the struggle of amoebomorphous cells (phagocytes) against infectious microbes in animal organisms, for instance in the Daphnia magna.
Most of these Russian students of nature exercised a great influence on the pupils who continued their
