OF WASHINGTON. 153 
Hulst to sustain his position on this matter. I may briefly notice, how- 
ever, a little satire which he indulges in at my expense, and a quite irrele- 
vant assertion which happens also to be incorrect. 
As one deeply interested in apiculture and a practical bee-keeper twenty- 
seven years ago, it was, perhaps, unpardonable in me not to qualify the 
statement about bees not being attracted to white flowers. Both Miiller, 
in his " Alpenblumen," and Lubbock, in "Ants, Bees, Wasps, "etc., have 
shown that bees prefer blue and purple to white flowers, and this is what 
was meant on the face of my language, so to cpeak; but Mr. Hulst has 
naturally made the most of the lapsus, and scored a point where every 
other point is against him. 
The assertion which I would call attention to, and which is entirely be- 
side the question at issue, is that "we are indebted to Dr. Engelmann for 
the discovery of the fact that Pronuba is an agent in the fertilization of 
Yucca." 
Whatever may have led Mr. Hulst to make this assertion, it is simply 
untrue, and the facts, which I may as well put on record here, are these : 
In June, 1872, Dr. Engelmann, who then knew full well that Yucca needed 
extraneous aid in fertilization, called my attention to this fact, and to the 
further fact that insects, especially white moths and soldier-beetles ( Chau- 
liognathns), were common in the flowers. He made no observations what- 
ever upon insect pollination, but wished me to study the question. The 
discovery that Pronuba was the agent was my own, as were all the subse- 
quent discoveries in reference to the insect made that year; but they were 
always communicated to him, and often shared with and witnessed by him. 
My first paper on the subject was read in August, 1872, before the A. A. A. S., 
at its Dubuque (Iowa) meeting, and presented to the Academy of Sciences 
of St. Louis at the meeting for September 2, 1872. Dr. Engelmann's "Notes 
on the genus Yucca " were presented to the same Academy September 16, 
1872. Both papers are printed in vol. iiiof the Transactions of the Academy, 
Dr. Engelmann's preceding, because leading up to mine. In his paper 
Dr. E. says : "The suspected insects were handed over to my friend Mr. 
C. V. Riley, who thereupon took up the zoological part of the investiga- 
tion, the surprisingly interesting results of which are detailed by him in the 
succeeding paper" (Trans., etc., iii, p. 19), and I distinctly express my in- 
debtedness to him " for drawing my attention to the fact that the plants of 
this genus must rely on some insect or other for fertilization." It is quite 
probable that but for Dr. Engelmann's suggestion I should never have 
made the investigations, and he should share with me whatever honor at- 
taches to the discovery. If this is what Mr. Hulst means his language is 
unfortunate. Dr. Engelmann was, during my residence in St. Louis, at once 
my friend, companion, and master in natural history matters, and I have 
too much reverence for his memory to allow to pass unchallenged what he 
himself would repudiate were he still among us. As soon as I had learned 
that Pronuba was the agent he sent a brief announcement to the Bulletin of 
the Torrey Botanical Club (vol. iii, No. 7, July, 1872, p. 33) rather hastily 
