cytology

Looks like she also taught at Harvard, and as a visiting lecturer at Howard Payne College in Texas: texashistory.unt.edu/ark:/67531/metapth128368/m1/1/ She was married to a fellow academic, sociologist Pitirim Alexandrovitch Sorokin (1889-1968). They had two sons. Here's her husband's Wikipedia entry: en.wikipedia.org/wiki/Pitirim_Sorokin His papers are at the University of Saskatchewan: library2.usask.ca/sorokin/about His mentions of his family, in a memoir essay: "To finish this brief sketch of my life I must mention that in 1917, during the Revolution, I was happily married to Dr. Helen Baratynskaya, cytologist-researcher in her own right. She has published a number of her studies in botanical and other biological journals and is still continuing her research. For the forty-five years of our married life we seem to have had, as yet, neither time nor sufficient reason for divorce or separation. We have two sons: Dr. Peter P. Sorokin, research physicist with IBM, and Dr. Sergei P. Sorokin, instructor and research associate at Harvard Medical School." cliffstreet.org/index.php/external-course So this is one of her sons: en.wikipedia.org/wiki/Peter_P._Sorokin

Another view of Kathleen Blackburn taken at the same time (that also shows her left hand) can be seen here:

"Kathleen Beyer Blackburn (1892-1968), sitting in chair" by Smithsonian Institution
                                 

Her Wikipedia entry: en.wikipedia.org/wiki/Ruth_Colvin_Starrett_McGuire