402 OUTLINES OF EVOLUTIONARY BIOLOGY 



of sexual reproduction are so remote, that the ova and spermatozoa 

 have to be produced in vast numbers to compensate for the 

 immense mortality which must take place amongst them and 

 amongst the young animals to which they may give rise. Thus 



FIG. 184. The Dodder, Cuscuta europcea. Part of a Plant parasitic on a 

 Branch of Willow, with germinating Seedlings on the right and 

 Section of Host and Parasite on the left. (From Strasburger. ) 



b, vestigial leaves ; Bl, flowers ; Cus, stem of parasite in section ; H, haustoria of parasite 

 in section; W, stem of host in section, with vascular bundles (v, c) ; t, seedlings. 



one of the most frequent results, or at any rate concomitants, of 

 parasitism, and one which is well exemplified in the case of 

 Sacculina, is hermaphroditism, which affords many more chances 

 for the fertilization of the eggs than the unisexual condition. 



We meet with precisely analogous phenomena in the case of 

 many parasitic plants. In the dodder (Fig. 184) the leaves and 



