1892.] The Difficulties in the Heredity Theory. 543 
First Second Third 
generation. generation. generation, 
ne 
Uneoeser--—a 
Vise eeressseustoe®s 
f. o., fertilized ovum or embryo, containing materna) ar nd paternal characteris S, soma, Baires aer body, 
containing #, $, mt, d, v, somatic ya of the various tissues ; and G, germ-cells af Pi 
i HisroGEnesis.—Showi ing the successive rise G, and union f. 0. of the maternal and paternal come by 
direct histogenesis. 
Il. PANGENESIS.—Showing the tissues of the body S, ae to the germ-cells G, so that each f. o. is 
con of elements from both eg somatic and germ-ce! 
IIL. Conrinurry.—Showing th ivision of the embryo, J- 0., into somatoplasm, s (from which arise the 
body-cells), and germ-plasm, G ( cells Js 
