T HE 
December, 190r. No. 420. 
REGENERATION IN THE EGG, EMBRYO, 
i AND ADULT. 
T. H. MORGAN. 
term *regeneration" has come to mean not only the 
"cement of a lost part, but also the production of a whole 
nism from a piece of an animal or of a plant. There are 
Other phenomena that must be included under the same 
» Such as, the production of a part different in kind from the 
t, and also, as I shall try to show, those cases in which 
of an egg or of an embryo produces a whole or a part of 
ism. It appears that there are two principal modes by 
I regeneration takes place. The first and more familiar pro- 
followed by the development of new organs out of this 
by means of the formation of new tissue at the exposed 
