THE AMERICAN ENTOMOLOGIST. 



out several (that of the dependence of 

 clover upon cats, being perhaps the most 

 familiar), but which, apart from that gro- 

 tesqueness which they sometimes possess 

 on a superficial view, are among the best 

 illustrations of that intimate and far-reach- 

 ing consensus which pervades all depart- 

 ments of life. 



Considering to what extent man is de- 

 pendent upon the Palmaccm, Rosacece, and 

 other fruit and nut-bearing trees and plants, 

 which, at least on the theory of man's 

 simian origin, must have been far greater 

 if not absolute in the early period of his 

 existence ; considering, too, in connection 

 with this, that it is the Hymenoptera that 

 have contributed most to render the exist- 

 ence of this class of vegetation possible, 

 it ceases to be a mere poetic fancy to 

 claim for the bee and the ant the high 

 merit of having literally prepared the way 

 for the advent of man, whose prototype 

 they are to so great an extent, both in their 

 psychic and their social attributes. 



The works of Darwin, Lubbock, Hilde- 

 brand, and Hermann Midler, contain an 

 immense array of evidence bearing upon 

 ' this interesting subject of cross-fertiliza- 

 tion by insect agency, and I will only refer 

 to a few typical cases peculiar to this 

 country, and for the most part omitted in 

 those works. Our American flora certainly 

 presents as promising a field for this line 

 of research as that of any other portion of 

 the globe. Our Orchids are more varied 

 and beautiful than those of Europe, and 

 their peculiar forms doubtless embody les- 

 sons not yet imparted to man. The Asclc- 

 piadacecB of which we have a rich abund- 

 ance, depend wholly upon insects to extri- 

 cate the pollen-masses from the deep cells 

 in which they would otherwise remain 

 permanently imprisoned. Our Mountain 

 Laurel, Kalniia latifolia, has its anthers 

 embedded in pits in the corolla from 

 which, when freed by insects working at 

 the nectar tubes below, they fly back by 

 the elastic spring of the filaments, and cast 

 their pollen to distant flowers. Houstonia 

 purpurea and H. ccerulea, as also Mitchella 

 repens and other RubiacecB furnish marked 



examples of heterostyly, while cases of di- 

 chogamy are common among the Geraniacece. 

 Umbellifene, Composites and Gentianacece. 



Science is indebted to two distinguished 

 citizens of St. Louis, for the double dis- 

 covery that our beautiful Yucca filamentosa 

 is fertilized wholly by insect agency, and 

 that this is accomplished by a single species 

 of insect without whose services it can not 

 bring forth fruit. 



Most of you doubtless remember the bril- 

 liant paper by Prof. C. V. Riley, read at the 

 Dubuque meeting of this association in 1 87 2, 

 in which these discoveries, the first made 

 by Dr. George Engelmann and the second 

 by himself, were announced, and Pronuba 

 yuccasella was formally christened. 



This case has an especial interest in con- 

 nection with the general subject of this 

 paper, since it illustrates more pointedly 

 than any other within my knowledge, the 

 nature of that consensus which exists be- 

 tween the insect world and the world of 

 flowers, and at the same time forcibly de- 

 monstrates the necessity of studying these 

 two sciences in connection. 



Without enumerating additional in- 

 stances, I may be permitted to refer to my 

 own recent observations on Sabbatia angu- 

 larts, whose curious behavior seems to me 

 to admit of no other interpretation than as 

 designed to secure the prevention of self- 

 fertilization. 



This flower, which is very showy and 

 handsome, contains 5 stamens with elong- 

 ated, sagittate, introrse anthers, which are 

 abruptly curved outward near the summit, 

 and a single style about as long as the 

 stamens terminated by a forked stigma 

 nearly as much longer, the commissure 

 being often visible as a distinct line to near 

 the base of the style. 



These branches of the style which are 

 stigmatic on the inside, are at first closely 

 twisted together in such a manner as to 

 conceal the stigmatic portion. They after- 

 wards untwist and present the simply bi- 

 furcate appearance. 



The plant is protandrously dichogamous 

 and this untwisting of the stigma lobes 

 does not take place until the anthers have 



