on the Stigma in Campanulaceae, fyc. 85 



Stigma in the Fecundation of Campanulaceae/ contained in 

 a recent Number of the e Annals/ and translated by W. A. 

 Leighton, Esq. To this subject, previously to the appearance 

 of these remarks, I had paid some attention. I do not, how- 

 ever, concur in all the conclusions arrived at by that able in- 

 vestigator. 



If the flower-bud of any of the Campanulas be examined a 

 day or two prior to the expansion of the corolla, the sta- 

 mens will be observed to envelope and conceal the whole sur- 

 face of the pistil. If it be again examined, about the period 

 of the unfolding of the blossom, the anthers may be seen to 

 open and disclose their contents. As soon as this has oc- 

 curred, the stamens having performed the office allotted them, 

 begin to wither away, in consequence of the juices destined 

 for their nourishment being now directed into a new channel. 

 The pistil, immediately on the dehiscence of the anthers, in- 

 creases rapidly in size, carrying with it in its upward pro- 

 gress, (as by a brush) by means of the hairs upon its surface, 

 the pollen granules. This increase, amounting frequently to 

 thrice the original length of the pistil, arises, partly, from the 

 excitation of the new action now set up in it, but mainly from 

 the accession of the nutriment formerly sent to the stamens, 

 but now no longer required by them. 



These hairs are found in all the Campanulaceae, save only 

 the small genus Petromarula, extending from the base of the 

 style to the apex of the stigma, externally, and arranged in 

 lines, corresponding in number and position with the sta- 

 mens ; they are directed horizontally and slightly curved at 

 their extremities. Their surface is lubricated by a secretion, 

 or perhaps, I should rather say, an exudation, serving to 

 retain the pollen in contact with them. The office per- 

 formed by these hairs is undoubtedly purely mechanical, 

 acting, first, as collectors of the pollen, and subsequently, as 

 props, to sustain it in contact with the fecundating surface — 

 entangled amidst the hairs it is not readily scattered or dis- 

 turbed. Adolphe Brongniart's account of the anatomy of the 

 hairs I consider to be satisfactory ; although I do not deem 

 his comparison of their retractile movements to that of cer- 

 tain Annelides, or the tentacula of snails, to be at all analo- 

 gous, the phenomenon in the latter cases being voluntary and 

 vital, the result of complex organization ; and, in the former, 

 merely mechanical, presenting nothing peculiar or extraor- 

 dinary in its nature, but arising simply from the absorption 

 or drying up of the fluid contained in the hair itself, and in 

 the expansion at its base*. 



* The retraction of the hairs does not take place until some days after 

 the application of the pollen, the greater part of which then falls offin con- 



