Note 135 — THE INDIVIDUAL ORGANISM WITH REGARD TO FORM AND METABOLISM (continued 4)

Boveri tried to fertilise enucleated fragments of the egg of Sphaerechinus with the sperm of Echinus. He failed to get any results in isolated experiments, but found a few small larvae of the pure Echinus type in large cultures consisting of shaken eggs. But later experiments on hybridisation in sea-urchins have shown that a full hybrid of Echinus and Sphaerechinus may be purely paternal also.