369 



against all influences, such as the condition oftbe plant and the weather, 

 which might affect or vitiate the results. These may be summed up 

 thus: 



(1) Dr. Englemann's limit of time during which fertilizations may 

 take place must be extended so as to include the second evening, and 

 even the second morning, after tbe opening of the flower. 



(2) Xo seed has been produced by merel}' touching the apices of the 

 stigma with the pollen, though partial fertilization may take place and 

 cause the growth of the fruit for a varying iDeriod, generally' only three 

 or four days. When the pollen is thrust into the tube (the mode of 

 conveyance making little difference) fertilization is much more certain, 

 but even here is rarely sufficient to produce ripe seed, the upper part of 

 the pod often filling well, but the basal part not filling, and at last 

 withering, so that the fruit ultimately falls off' before ripening. 



The conclusion is inevitable that angustifoUa is more susceptible to 

 artificial pollination than the species which I experimented witb, and 

 that Pronuba far excels man in the perfection "^ith which she performs 

 the act. She has the power of fertilizing all the ovules, at which no 

 one will wonder who has carefully watched her, because the act of pol- 

 lination is normally- repeated several times, first from one of the angles 

 between the apices, then from another, and, as Prof William Trelease 

 has shown, the tongue is used, in addition to tbe tentacles, to push the 

 pollen down to tbe bottom of the tube. 



2d. I have made careful search the past summer, and have had my 

 associates, Messrs. Howard, Pergande, and Lugger, assist in the search 

 for honey-bees in or about the Yucca flowers in Washington. Tbere 

 were over two hundred stalks under observation, most of tbem of easy 

 access, on the grounds of the Department of Agriculture. Neither of 

 the tbree gentlem* n mentioned detected any bees, but I succeeded on 

 two occasions, and each time between 9 and 10 a. m., in finding a single 

 bee flying about tbe flowers. In neither case did the bee make any at- 

 tempt to enter, but in each it probed around tbe outer base of tbe flower 

 in searcli for nectar, and soon left evidently without being able to get 

 much. Tbese facts I record not in any way to cast discredit on Mr. 

 Hulst's statement, but rather to show how very different from bis own 

 has been my experience in this direction, both in St. Louis and Wash- 

 ington. Not that I placB much faith in the constancy of bees, which 

 are known to be somewhat fickle in their tastes a-ccording to season or 

 colony, a fact that may account for the difference in our experience, as 

 may also the presumption that Apis meUifica is more abundant in 

 Brooklyn than in Washington, or, again, tbe known fact that Yucca an- 

 giistifoUa is less scant in nectar than its filamentose congener. Be that 

 as it may, our Apis has plainly, so far as observed, been after nectar, 

 and has shown no disposition whatever to go near tbe stigma, and this 

 fact is, as I have learned, corroborated by Professors Cook and Beal, 

 of the Michigan State Agricultural College, where, for the first time 



