DIV. n SPERMATOPHYTA 577 



modes of reproduction that can often be distinguished only by 

 careful investigation. In place of the various expressions used by 

 STRASBURGER and WINKLER which involve obscurity, the definitions 



Fin. 5'iO. Haustoria of the embryo-sac of Melampyrum nemorosum (after BALICKA-IWAXOWSKA). 

 b, Haustoria of the chalazal end ; c, nutritive tissue ; d, branch of the vascular bundle ; e, 

 funicle ; /, embryo; (/, the suspensor; a, a lt a y/ , haustorial tubes arising early from the micro- 

 pylar end, spreading widely in the funicle and sometimes penetrating the epidermis ; h, the 

 base of attachment of these ; i, cross-walls in the tubes. 



of A. ERNST ( 10 ) may be employed. According to him PARTHENO- 

 GENESIS is the apomictic (i.e. resulting without fertilisation) develop- 

 ment of gametes (especially egg-cells) of a sexually differentiated and 

 sexually functional plant or animal, whether the process is autonomous 



2P 



