v] 



LATER PROGRESS 



129 



The whole proceeding is of great interest, showing 

 as it does the blind and instinctive nature of the 



Fig. 13. The Yucca and its Moth (Pronuba yuccasella). A, ovipositor 

 of the moth, op, its sheath; sp, its apex; op', the protruded 

 oviduct. B, two ovaries of the Yucca, showing the holes by which 

 the young moths escape, and (r) a caterpillar in the interior. C, 

 head of the female moth, with the sickled-shaped process (si) on 

 the maxillary palps for sweeping off the pollen and rolling it into 

 a ball, mx', the proboscis ; au, eye ; p' t base of first leg. D, longi- 

 tudinal section through an ovary of the Yucca, soon after the 

 laying of two eggs (ei). stk, the canal made by the ovipositor. 



organisms' actions, and giving us an example of two 

 species absolutely dependent on each other for their 



H. 9 



