FERTILIZATION 



155 



vascular plants, and many others have made a tacit renuncia- 

 tion. To say that all the figures that have been drawn have 



Fig. 71. — Double fertilization. A. Helianthus annuus, showing the two coiled male 

 nuclei, one fusing with the egg-nucleus and the other with the endosperm nucleus; 

 after Nawaschin.* 1 B, Ira, the two polar nuclei not yet fused; after Guigxard. 3 * 

 C. Silphium laciniatum: spt, up?, male nuclei: o, oosphere; e, endosperm nucleus; 

 sy, synergid ; pt, pollen-tube ; x, two conjectural bodies often seen in the pollen- 

 tube after the male nuclei have been discharged : x 525 ; alter Land. 38 



been mere products of the imagination would be a radical state- 

 ment, and one doubtless verv far from the truth. In our 

 opinion the observations, figures, and descriptions, like the 

 pollen-tube embryos of Schleiden and Schacht, furnish an exam- 

 ple of the extent to which even a careful and conscientious 

 scientist may be influenced by preconceived opinion. 



Our knowledge of the phenomenon called " double fertili- 

 zation " (Fig. 71) dates from 1898, when Nawaschin 33, 34 an- 



