What next, indeed? Nobody really knows what the future holds for mid-life women in this country, and even this 54-year-old professor (Sociology, Boston U.) can only make tentative stabs at categorizing ten interrelated species. Jacobs, who raised a family herself before pursuing a B.A. at age 36, is more fair than most to the ""nurturers,"" variants of which comprise three categories; rather than siphon them off to fern-consciousness goals, she'd like to ""re-engage' them in paid nurturing roles after their mothering days. But unsupported generalities abound. Jacobs blithely contends, for instance, that ""if we really staffed our educational and public services properly, there would be plenty of paid work for nurturant mid-life women"" (though she does acknowledge a trend away from public spending for such projects). And when ""careerists"" are dubbed overqualified, that's ostensibly because ""employers feel threatened by them and would rather hire someone younger and less able but more subservient."" Most affecting is the plight of the ""escapists and isolates""--like the 1940 debutante, widowed in the War, who nursed older family members through final illnesses, became a lonely alcoholic, and died in an institution, ""a victim of social isolation."" The highest accolades go to the ""advocates"" who push for reform, particularly in respect to the twin discriminations of ageism and sexism, and the most ringing exhortation is for mid-life women to become the agents, not the victims of change. Hardly penetrating--but as a framework for further discussion, not without its value.