Kono Yasui

What sort of research did she do?

The microscope that Kono Yasui used in some of her pioneering research.

Dr. Yasui's first research project was an anatomical study of the carp's Weberian apparatus, a group of small bones that transmit sound in fish (comparable to the three small bones of the middle ear in mammals). The same professor then suggested that she do her next project on leech eggs, but Yasui simply could not warm to the idea of working with leeches, so she came up with her own subject, the aquatic fern Salvinia natans.

Unlike flowering plants, ferns propagate by spores, which grow into prothalia (singular: prothalium) bearing both male and female sex organs on their underside. She closely studied the process by which the egg cell was fertilized, divided, and brought forth a new fern. The paper in which she detailed her findings came to the attention of Professor Kiichi Miyake of the Tokyo Imperial University Faculty of Agriculture, who helped her get it translated and published in a British botanical journal. This was the first scholarly treatise by a Japanese woman ever published in a foreign academic journal.

What was the subject of Kono Yasui's best known work?

Yasui using a microtome to slice a piece of coal thin enough to examine with a microscope (1920).

The research for which Kono Yasui is most famous is her study of coal and the plants from which it was formed. This began while she was studying in the United States, at Harvard University, where she learned the methods required for such research. Coal is created from accumulated plant matter that carbonizes over millions of years, including not only hard objects like tree trunks but also pollen, spores, and resin. That means that by studying coal carefully, one can learn a great deal about the kinds of plants that existed as far back as the Tertiary Period (65 billion to 2 billion years ago).

After returning to Japan, Dr. Yasui visited coal mines all over the country to collect coal samples. Studying these samples, she examined the changes that occurred in the cell membranes as carbonization progressed by observing changes in light reflection and refraction. She observed the form, number, and arrangement of such vascular tissue as tracheids and fibers and compared them with those in modern plants, including gymnosperms and tree ferns, and in this manner she was able to deduce what sorts of plants made up any given coal sample. It was perhaps lucky that Dr. Yasui chose to study Japanese coal, in which the degree of carbonization tends to be fairly low, which means that the plant tissue is left relatively intact. Dr. Yasui embedded the plant fossils she found in celloidine (a flexible substance resembling plastic), which she then hardened and cut into thin slices for microscopic examination.

In a paper titled "Studies on the Structure of Liguit, Brown Coal, and Bituminous Coal in Japan," Dr. Yasui detailed her findings, demonstrating that the cellulose in the cell membranes diminished as carbonization progressed. Especially impressive was the way she made her own deductions about Japanese flora during the Tertiary Period from the fossils she observed. To describe extinct plants from the age of fossils required an enormous amount of study and expert judgment, and the scientific names of these plants even now bear her name. On the basis of this paper, Kono was awarded a doctoral degree in 1927 and became Japan's first woman doctor of science.