The introduction of testing methods for sex hormones not only changed medical practices but also transformed the meanings science assigned to sex differences in different respects.

First, in the process of testing we see how scientists gradually became more and more remote from common-sense opinions and everyday language. In the early period of hormonal research, scientists still used concepts that were closely related to common-sense notions of masculinity and femininity. Based on their test methods, sex endocrinologists defined sex hormones as substances originating from ovaries and testes, a conceptualization which strongly resembles the prescientific idea of the ovaries and testes as the seat of femininity and masculinity. Entering more deeply into the laboratory, we encounter an increasingly specialized technical language and conceptualization of sex hormones. In their later experiments, gynecologists defined sex hormones as substances regulating the growth of the uterus. When biologists and chemists enter the field, we see a wide variety of statements about hormones with an increasing array of technical details:

1 female hormones induce the cornification of the epithelial cells of the vagina in ovariectomized mice

2 the extracts of bull testes induce the growth of the atrophic comb of the capon

3 male sex hormones are steroids, melting point 183.5-184.5°C, and are alkali labile

4 the molecular formula of testosterone is C19H28O2.

This list of statements reveals how, in the process of testing, the culturally based definition of sex is gradually replaced with an increasingly technical account of sex and the body.

Second, in choosing specific test methods for sex hormones, scientists not only introduced a technical account of sex, but also specified the meanings they assigned to sex. In Chapter 2, we saw how sex endocrinologists gradually abandoned the original assumption that each sex could be recognized by its own sex hormone. Instead, sex endocrinologists introduced a quantitative theory of sex in which male and female sex hormones are present in both sexes. Men and women differ only in the relative amounts of then” sex hormones. The introduction of tests for measuring sex hormones provided sex endocrinologists with the tools to specify this quantitative theory. Based on the female sex hormone blood test, gynecologists now suggested that men and women could be characterized by the specific nature of their hormone regulation, emphasizing the cyclic nature of female sex hormone production in women and the continuous, stable nature of male sex hormone production in men (Frank 1929:113, 292). Sex endocrinology thus attached the quality of cyclicity to femininity, and stability to masculinity.

The emphasis on cyclicity is also reflected in the naming of one of the female sex hormones. One of the two types of female sex hormones was renamed “estrogens”, thus referring to the specific test method for female sex hormones: the cyclic changes in the vagina characteristic of estrus, the period of sexual activity and fertility. By choosing the name estrogens, sex endocrinologists emphasized the cyclic nature of female reproductive function. Although cyclicity can have positive connotations (cyclicity means regularity) as well as negative connotations (cyclicity means instability), scientists emphasized the latter. The next quote from a Dutch gynecologist exemplifies how scientists associated femininity with lability:

Throughout her entire life the woman is controlled by the rhythmic function of her ovaries, and the changing hormonal content of her blood causes a major psychological and bodily lability. For men such a problem does not exist. This is the reason why women are handicapped in then” struggle for equality with men.

(Snoo 1940:3,940)

In Chapter 4, we shall see how the association of femininity with cyclicity also affected medical practice. This association has functioned as paradigmatic both in later studies and medical practice with respect to many different aspects of the female body. The emphasis on the cyclicity of female reproductive functions disclosed the possibility of medical intervention into the cyclic functions, like intervening into the length of the menstrual cycle by administering hormones.

Finally, the introduction of tests also created extensive changes in the sex labeling of physical features. In this process, sex endocrinologists redefined what had to be considered as male and female characteristics. The manner in which scientists redefined male and female characteristics is nicely illustrated in the Handbuch der biologischen Arbeitsmethoden, one of the first handbooks on biological research methods, published in 1938. In the chapter dealing with research techniques for male sex hormones, male characteristics are classified into three categories: physical characteristics, psychic characteristics and neutral characteristics (J. Freud 1938:1,671). In the context of this study, the last category is of particular interest. Neutral characteristics are denned as those male or female features that do not change after castration or ovariectomy. With this premise endocrinologists actually redefined what should be considered as male or female characteristics. Physical features considered as typically male or female before endocrinology emerged were now considered as sex-neutral. For example, the feathers and spurs of domestic fowl, with striking differences between males and females, were no longer classified as male or female characteristics but as neutral features.

Other scientists argued, however, that these features should not be classified as sex neutral. Dutch and British scientists introduced a new classification of sex characteristics. In addition to male and female characteristics, they suggested using the categories of “negative masculine” and “negative feminine.” In contrast to what endocrinologists had expected, the gaudy plumage of roosters seemed to be controlled not by male sex hormones but by female sex hormones. In domestic fowl, castration of the male had no effect on the feathers, whereas ovariectomy of the female resulted in the male type of feathering. Thus, in the terms of endocrinologists, a hen is hen-feathered because her “male” plumage is suppressed by the activity of female sex hormones (Callow and Parkes 1936:7). Features like the plumage of roosters were now redefined as “negative feminine” characteristics (Jongh 1951:20).

Hair growth on the heads of men confronted endocrinologists with similar problems. This hair growth was considered as a feature stimulated by male sex hormones. Consequently, hair growth was considered a typically masculine characteristic. Following this definition, the phenomenon that men usually lose their hair with increasing age could no longer be considered as masculine. Endocrinologists renamed this feature as “negative masculine.” (Jongh 1951:20).

Sex endocrinologists thus redefined the sex labeling of physical features. Following the basic criterion for sex hormones embodied in the biological tests, only those functions and characteristics whose development was stimulated by male or female sex hormones were still entitled to be labeled masculine of feminine. Features that were not controlled by sex hormones were considered as sexually neutral, whereas features whose development was suppressed by sex hormones were labeled as “negative masculine” or “negative feminine.”