THE PRODUCTION OF GRAFTED EMBRYOS. 



95 



(d) Fusion with partially double archenteron. 



(e) True fusion with a single set of organs. 



(/ ) Single body with a second parasitic archenteron. 



Some of these types he obtained from Echinus microtuber- 



FIGS. 85-89. 



culatus only, types a, b, c, d and e\ others from Sphcerichinus 

 gramdaris, types e and /; and some from both of these echino- 

 derms, type e. 



