Theodor Boveri

Boveri studied reproductive cells in Ascaris worms, whose relatively few chromosomes made their behavior easier to follow. His observations connected the reduction in chromosome number during germ-cell maturation with the contributions brought together at fertilization.

References: [1]

Boveri investigated abnormal development after two sperm entered a sea urchin egg. Subsequent divisions could distribute different chromosome combinations to the daughter cells. Comparing the resulting embryos helped him examine whether development depended simply on chromosome quantity or on the presence of particular chromosomes.

References: [1]

He concluded that both parents contributed chromosomes through their reproductive cells and that normal development required an appropriate, complete complement. Chromosomes that looked alike were therefore not necessarily interchangeable: individual chromosomes could carry different hereditary qualities. This connected microscopic observations with an explanation of inheritance.

References: [1]

In 1893 Boveri became professor of zoology and comparative anatomy at the University of Würzburg, where he remained until his death in 1915. Nettie Stevens visited his laboratory. Such exchanges connected his cytological investigations with other researchers studying fertilization, chromosomes and heredity.

References: [1]