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Note OH Dr. Hartig's New Theorij of the Fertilization of Plants. 

 By William Wilson, Esq. 



In this department of science it is far more easy to speculate than 

 to make discoveries, and I fear that until more facts are obtained, and 

 the reputed facts more thoroughly established, theories will only tend 

 to mislead. It is incumbent on me here to make a confession of er- 

 ror on an important point connected with that part of Dr. Bartig's 

 theory which treats of fertilization by means of the style. I do so 

 with less hesitation now that my former statements (which were nei- 

 ther hastily nor carelessly made) have been confirmed by such highly 

 respectable authority. I have waited for years in full expectation 

 that some one would spare me the task of self-refutation. 



True it is, that the pollen-grains of Campanula do enter the hairs 

 of the style, and that they are sometimes to be found [e. g. in Cam- 

 panula Rapunculus, where the hairs are of greater diameter) in con- 

 siderable abundance ; but the manner in which they get there is the 

 question. During my prolonged examination (continued without 

 intermission for days) I was not unaware of the danger of making 

 false deductions, and I thought that I used sufficient precautions 

 against them ; but after all, I am now persuaded that an error (a par- 

 donable one, as I hope) must have been committed ; for I could not, 

 in the following year, detect a single pollen-grain in the hairs of any 

 style previous to dissection, and I had already ascertained that pol- 

 len-tubes are developed in the usual mode upon the stigma of C. Ra- 

 punculus. It is my present opinion that the pollen-grains obtain 

 access to the interior of the hairs of the style precisely at the moment 

 when the sections are made with the cutting instrument, and that 

 they enter at the base, which then becomes open and exposed, and 

 not at the apex. 



Of course, I cannot join with Dr. Hartig in regarding it "as de- 

 cided that fertilization takes place by means of the hairs ;" nor is it 

 yet sufficiently clear to me, though it is not improbable, that the re- 

 traction of the hairs (which, however, does assuredly cause a species 

 of absorption of the pollen-grains into the substance of the style) is 

 essentially productive of fertilization, on the part of the included pol- 

 len-grains, which do not (so far as I have observed) put forth tubes 

 within the usual period of fecundation, nor for a considerable time 

 afterwards, if at all ; nor do they appear to be otherwise altered. 



W. Wilson. 



Oiford Mount, September 1, 1847. 



Vol. II. 6 e 



