This dissertation describes how and why the source of raw silk, the domesticated silkworm (Bombyx mori), emerged as an organism that scientists in Japan researched intensively during the late nineteenth and early twentieth centuries. People invested in and exploited the lucrative silkworm in order to produce a delicate fiber, as well as to help impart universal claims and ideas about the governing patterns of inheritance at a time when uncertainties abounded about the principles of what we today call genetics. Silkworm inheritance studies such as those by scientists Toyama Kametarō (1867- 1918) and Tanaka Yoshimarō (1884-1972) contributed to ideas developing among geneticists internationally about the biological commonalities of different living organisms. Silkworm studies also interacted with the registration of silkworm varieties in and beyond East Asia at a time when the rising Imperial agenda intertwined with the silk industry. Different motivations drove silkworm science, apparent in the growth of Japanese understandings of natural order alongside the scientific pursuits of universality. Tōitsu, a "unification" movement around 1910, notably involved discussions about improving silk and decisions about the use of particular silkworms to generate export-bound Japanese silk. I show why the reasons for classifying silkworms within Japan had as much to do with the connection between textiles, power, and social order as it did with the turn toward experiment-based biological articulations of inheritance, which together interacted with ideas about Japanese nationhood.