GROWTH AND TRANSFORMATION 197 



Of all aberrant cases of insect development perhaps the 

 most remarkable is the '' polyembryony '' of certain small 



Fig c5._Polyembryonic development of Platygaster vernalis a, 6, 

 egg undergoing maturation divisions (m, m') ; />', first polar body, s 

 spfrm-nucleus; ., d, conjugation of egg and sperm nuc ei o 5 to 

 form zygote nucleus (n) ; polar-bodies {p) mcreasmg m f^l^\>J^l^ 

 stage when the polar bodies have given rise to nu ntive ^dls (^a) the 

 trophamnion, surrounding the eight embryonic cells (« derived from 

 the zvgote-nucleus, X i350 ;/, 5^, stdl later; stages >,with embryo e) 

 developing from each embryonic cell. / X 700^ ^.X^^^^; ^*'^' 

 R. W. Leiby and C. C. Hill {Joum. Agr. Res., U.S.D.A. ig^S-) 



