100 liilcjj — fSoinc Interrelations of IHanfx ciid Inseds. 



particular case, out of the question, and that tlie (leveh)pnient 

 of the seed in tliis species is exclusively due to the stimulation 

 of the tissues caused by the puncturing of the Blastophagas ; in 

 other words, that these insects actually represent the male ele- 

 ment in the fertilization. This is certainly the most extraordi- 

 nary phenomenon in the history of fertilization, and if confirmed — 

 and Dr. (Aniningham has l)een most careful and circumspect in 

 his work — it will give a more striking instance than anv we have 

 hitherto obtained of the mutual interdependence which plants 

 and insects may attain and the surprising manner in which they 

 may modify each other. 



Gener.^lizatiox. 



The ])eculiarities which I have endeavored to present to you 

 are full of suggestion, particularly for those who are in the habit 

 of looking Ijeyond the mere facts of observation in endeavors 

 to find some rational explanation of them ; who, in other words. 

 see in everything they observe significances and harmonies not 

 generally understood. The facts indicate clearly, it seems to me, 

 how the peculiar structures of the female Pronuba have been 

 evolved by gradual adaptation to the particular functions which 

 we now find her performing. With the growing adaptation to 

 Pronuba's help, the Yucca fiowcr has lost, to a great extent, the 

 activity of its septal glands ; yet coincident with it we find an in- 

 crease in the secreting power of the stigma. This increase of the 

 stigmatic fiuid has undoulitedly had much to do with originally 

 attracting the moth thereto, while the pollinizing instinct doubt- 

 less became more and more fixed in proportion as the insect lost 

 the power or desire of feeding. With the mind's eye I can look 

 back into the past and picture tlie gradual steps by which the Pro- 

 doxids to which 1 have alluded have differentiated along lines 

 which have resulted in their present characteristics. On the one 

 side I see variations which liave become sufficiently fixed to l^e 

 considered specific ; yet which can have no especial bearing on the 

 life necessities of the species, but are a conseijuence rather of 

 that universal tendenc}^ to variation with which every student 

 of Nature becomes profoundly impressed. Thus the wing-mark- 

 ings vary from a darker general coloring, as in Prodo.cus aiticscens, 

 to a more uniform intermixture of the black scales among the 

 white, as in cinereus^ or a sparser intermixture thereof, as in pulcer- 

 ulentns. The disposition of the black scales is in s])ots or bands, 

 whether transverse or longitudinal, as in nnirf/iiiatii-'^, reticnlatns, 



