Boveri, Theodor Heinrich (1862–1915)

German biologist. He showed that it is not a specific number but a specific assortment of chromosomes that is responsible for normal development, indicating that individual chromosomes possess different qualities.

Boveri was born in Bamberg, Bavaria, and studied at Munich. From 1893 he was professor of zoology and comparative anatomy as well as director of the Zoological-Zootomical Institute in Würzburg.

In 1889 Boveri experimented on sea urchins' eggs, fertilizing nucleated and nonnucleated fragments, and found that both types could develop normally; occasional nonfertilized fragments containing only a nucleus were also able to develop normally. He showed that at fertilization the egg and the spermatozoon incorporate the same number of chromosomes each in the creation of the new individual. Eventually he was able to demonstrate that cytoplasm (the part of the cell outside the nucleus) plays an important part in development.

He also studied tumours, believing that malignancy may result from abnormal chromosome numbers. He was the first to realize tumours formed when cells malfunctioned.