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STRASBTJRGER ON FOREIGN POLLINATION. 



THOMAS HICK, B.A., B.Sc, 

 Demonstrator and Assistant Lecturer in Botany, The Owens College, Manchester. 



Botanical readers of the Naturalist will probably remember that in 

 the last volume some account was given of Strasburger's New Investi 

 gations on the process of Fertilisation in Phanerogams. In the course 

 of those investigations, foreign pollen grains were often met with on 

 the stigmas of plants, which had not only put forth pollen-tubes, but 

 had forced the same to a greater or less distance down the styles. 

 Struck with this phenomenon, and doubtless recognising its im- 

 portant bearing upon several physiological questions, Strasburger in- 

 stituted a series of observations and experiments, with the object of 

 determining within what limits the formation of pollen-tubes on 

 foreign stigmas is possible, whether any disadvantage is connected 

 therewith, and if so, whether there exist any protective contrivances 

 by which such a mode of pollination is, as a rule, prevented. The 

 results of the investigation he has recently published in a paper 

 which appears in the current part (Band xvii, Heft I) of Pringsheim's 

 ' Jahrbiicher fiir wissenschaftliche Botanik,' and which, like everything 

 from the pen of the Bonn Professor of Botany, will well repay close and 

 attentive study. The title of the paper is ' Uber fremdige Bestau- 

 bung,' which we have translated as above — 4 Foreign Pollination' — 

 and purpose in what follows to give a resume of the experiments made 

 and of the conclusions arrived at. In doing so, Strasburger's own 

 language will be followed as closely as possible, so that no injustice 

 may be done him by a misinterpretation of his statements. Of the 

 experiments themselves nothing need be said, save that they were 

 rigorous and numerous enough to ensure the reliability of the general 

 results, and that wherever possible the pollination was effected 

 reciprocally, that is, the stigma of A was dusted with the pollen of B, 

 and conversely the stigma of B with the pollen of A. 



The first plant to be experimented with was Fritillaria persica, 

 taken first in the early year. It was soon found that the pollen of 

 this plant is capable of forming pollen-tubes, not only on its own 

 stigma, but on those of other plants belonging to different genera, 

 and even to different natural orders. Thus the pollen grains germinate 

 on the stigmas of Convallaria latifolia, C. polygonatum, Tulipa Ges- 

 neriana, Scilla hispanica, S. non-scripta, Orchis mascula, and O. Morio. 

 The germination on Convallaria latifolia quite agrees with the normal 

 behaviour on its own stigma. The pollen-tube penetrates the stylar 



Dec. 1886. 



