CHAP. I.] Investigation of the fertilisation-process. 431 



conclusions respecting the relation of the structure of the 

 flower to the insect world. This Gartner entirely failed to do, 

 and hence in this case also it was reserved for Darwin's 

 wonderful talent for combination to sum up the product of the 

 investigations of a hundred years, and to blend Koelreuter's, 

 Knight's, Herbert's, and Gartner's results with Sprengel's 

 theory of flowers into a living whole in such a manner, that 

 now all the physiological arrangements in the flower have 

 become intelligible both in their relations to fertilisation, and 

 in their dependence on the natural conditions under which 

 pollination takes place without the aid of man. Here, as in 

 morphology and systematic botany, Darwin found the pre- 

 misses given and drew the conclusion from them ; here too 

 the certainty of his theory rests on the results of the best 

 observers, on investigations which find in that theory their 

 necessary logical and historical consummation. 



7. MICROSCOPIC INVESTIGATION INTO THE PROCESSES OF 

 FERTILISATION IN THE PHANEROGAMS ; POLLEN-TUBE 

 AND EGG-CELLS 1 . 1830-1850. 



THOSE who were convinced of the sexuality of plants had 

 endeavoured as early as the previous century to form some 

 idea with the help of the microscope of the way in which the 

 pollen effects the formation of the embryo in the ovule. We 

 may pass over Morland's and Geoffrey's very rude attempts in 

 this direction; Needham (1750), Jussieu, Linnaeus, Gleichen, 

 and Hedwig imagined that the pollen-grain bursts upon the 

 stigma, and that the granules it contains make their way down- 



1 The more important works referred to in this section are Robert Brown's 

 'Miscellaneous Writings,' edited by Bennett, 1866-67; von Mohl on G. 

 Amici, in the 'Botanische Zeitung,' 1863, Beilage, p. 7 ; Schleiden, 'Ueber 

 die Bildung des Eichens und Entstehung des Embryos,' in ' Nova Acta 

 Academiae Leopoldinensis,' 1739, vol. xi, Abtheilung I ; Hofmeister, 'Zur 

 Uebersicht der Geschichte von der Lehre der Pflanzenbefruchtung,' in 

 'Flora' of 1867, p. 119. 



