57 2 TRANS. ST. LOUIS ACAD. SCIENCE. 



(3) I have never noticed anything of the sort in my studies. 

 This is owing, doubtless, to the fact that they have been made on 

 the plants as they naturally grew, assisted by a confederate who 

 carried a dark lantern. The conditions surrounding Mr. Boll's 

 observations were unnatural, and to this circumstance or to pure 

 imagination must be ascribed the stated conduct of his moths. 



(4) Now, as I did not observe "the same thing in exactly the 

 same way," but observed and described something totally differ- 

 ent, viz., the thrusting of the pollen into the stigmatic tube (a?Ue, 

 p. 208), it is evident that Mr. Boll did not know what he was 

 writing about. In truth, as is patent from the article itself, and 

 as he has since confessed to me, Mr. Boll knew at the time abso- 

 lutely nothing of my writings on the subject except what he 

 learned through Prof. Zeller's notice. Further comment is need- 

 less. The fact that Yucca is not a self-fertilizer, I have demon- 

 strated (ante, p. 209) by excluding the moth : it does not rest on 

 my testimony, however, but is well known to all botanists who 

 have studied the genus. 



Following the portion of the article which I have translated is 

 a long dissertation on the nature of the Yucca flower, in which 

 we are vouchsafed the interesting information that the fruit can 

 only be fertilized through the stigma, and not through the walls 

 of the pistil ! The argument is also made, that the capsules 

 containing no Pronnba larvae must have formed without the aid 

 of the moth, notwithstanding I have conclusively shown that pol- 

 lination may, from one cause and another, be performed without 

 oviposition. The statement is reiterated about the self-fertilizing 

 power of the flower, against experience, experiment, and author- 

 ity. But the most amusing exhibition of Mr. Boll's logic is where 

 he explains the object of stuffing with pollen the punctures made 

 by the ovipositor, to be the closing of the wound, because the 

 "pollen as soon as it comes in contact with the sap, rapidly 

 swells"; and then, almost in the same breath, tells us that when 

 pollen is not forthcoming, the papillose hairs of the stamens are 

 gathered and used for the same purpose ! ! Do these swell, too? 

 The truth is that the puncture of the ovipositor is so fine that no 

 single pollen grain could be put into it, while the same will hold 

 true of the papillose hairs referred to, which, by the way, the 

 moth has no means of detaching, and for which Mr. Boll doubt- 



