ALDKIDGE ON I'OLLEN. 89 



was the probable (and experience has since shown it lo be the 

 actual) means used b}' nature in the process of impregnation. 



Before I conclude this part of the subject, I feel it neces- 

 sary to acknowledge that I have expressed Fritzche's views er- 

 roneously in the paper read before the British Association, 

 as relates to the influence of acids in coagulatinfj the fluid 

 contents of the pollen. I mentioned in that essay the grounds 

 upon which I conceived him to have overlooked this reaction ; 

 being at that time only acquainted with Fritzche's observa- 

 tions, from the notice of them contained in Lindley's intro- 

 duction. In this work, it is stated, that " in particular, he 

 (Fritzche) recommends the employment of sulphuric acid in 

 the proportion of two parts of concentrated acid to three 

 parts of water, for the purpose of viewing the pollen by trans- 

 mitted light; by this means it is rendered transparent^ and 

 the spontaneous emission of pollen-tubes is effected." ( Vide 

 Op. cit. p. 159.) Now, instead of acids rendering the pollen 

 grains transparent, I was led to the observation of the coagu- 

 lation of the fluid contents, by perceiving them to become 

 opaque under the influence of these agents. But the obser- 

 vations of Fritzche must have been misquoted by Lindley, 

 for in page 668, of the work before me, he distinctly states 

 that the mucus of the pollen-contents is coagulable by 

 acids. 



It appears then that as far as Fritzche is concerned, the 

 originality of the propositions, viz., " that the stigma is in- 

 variably acid at some period of its growth, and that it is in 

 consequence of this acidity that the pollen bursts," rests en- 

 tirely with me; and that my third proposition is confirmed 

 by the observation which deprives me of the merit of first de- 

 tecting it. I have been unable to obtain Miihl's work, but I 

 infer that if he had been aware of the acidity of the stigma, 

 Fritzche who wrote subsequently, could noC have been igno- 

 rant of it. 



I now leave the subject of priority, which I hope to be ex- 

 cused for having brought forward at all. Indeed, I feel 

 convinced, that the gentlemen whose names I have ventured 



Vol. IV.— No. 26. M 



