[1] Lascelles and William R. Sistron were credited with applying the emerging technology of pre-molecular genetics to the biosynthesis of the photosynthetic pigments called bacteriochlorophyll.

In 1956, Lascelles was awarded a Rockefeller Foundation fellowship, and went to Stanford University for a year to work with C. B. van Niel at the Hopkins Marine Station at Pacific Grove, California.

[3] Van Niel was legendary in his knowledge of microorganism biology, and this experience afforded Lascelles a great deal, especially the ability to study more exotic bacterial organisms.

She worked at dispelling the previously-thought rule that anaerobes do not have cytochromes, and the provision of a soluble β-hydroxybutyrate dehydrogenase, which allowed Krebs' group to devise a now widely used assay for ketone bodies.

These years were some of the most productive in her career, and her work provided the basis of understanding of tetrapyrrole synthesis in photosynthetic bacteria which holds tested and true even today.