371 



sect made that year ; bat they were always communicated to him, and 

 often shared with and witnessed b}' him. 



My first i^aper on the subject was read in August, 1872, before the 

 A. A. A. S.,at its Dubuque (Iowa) meeting, and presented to the Acad- 

 emy 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. Ill of 

 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. 0. Y. Riley, who thereupon took up 

 the zoological part of the investigation, tlie surprisingly interesting re- 

 sults of which are detailed by him in the succeeding paper " (Trans., 

 etc.. Ill, p. 10), and I distinctly express my indebtedness 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 investi- 

 gations, and he should share with me whatever honor attaches to the 

 discovery. If this is what Mr. Hulst means, his language is unfortu- 

 nate. 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 revereuce for his memory to allow to pass unchallenged what 

 he himself would repudiate were he still among us. As soon as 1 had 

 learned that Pronuba was the agent, he sent a brief announcement to 

 the Bulletin of the Torrey Botanical Club (Vol. Ill, No. 7, July, 1872, 

 p. 33), ratlier hastily referring to the insect as "a white moth of the 

 genus Tortrix,"and in a subsequent communication {ibid.^ August, 1872, 

 p. 37) he corrected the error and recorded some further facts in the life- 

 history of The insect. In neither case was there any claim of individual 

 discovery of the entomological facts, and these announcements must be 

 read iu the light of his subsequent more deliberate language, which I 

 have quoted. 



In conclusion, having already devoted more time to Mr. Hulst's opin- 

 ions than the^' justify, let me add that another year's study of Yucca 

 fertilization has not only served to confirm all that I have hitherto writ- 

 ten, but still further to enhance the importance of Pronuba to the plant 

 and the intelligent nature of her unique performances. Prof. William 

 Trelease, who has made the only other careful observations on the sub- 

 ject which have come to my notice, has demonstrated (Bull. Torrey Bot. 

 Club, Aug., 1886, pp. 135-141) that the stigmatic liquor is not nectarif- 

 erous, but that the slight amount of nectar associated with the tlowers 

 is secreted in thin pockets formed by the partitions that separate the 

 three cells of the pistil, and which open externally by a contracted pore 

 from which the nectar is poured through a capillary tube (inclosed by 

 the closely applied, but not outwardly united, lobes of the ovary) to the 

 base of the pistil, so that nectar-feeding insects seek it not about the 

 stigma, but at the base of the pistil or of the petals, whether within or 



