138 GYMNOSPERMS 



vacuoles at the top of the egg. A sperm is then drawn into the egg 

 so violently that the protoplasm, with its ciliated band, is torn off 

 and left near the top of the egg, while the nucleus moves downward 

 to unite with the egg nucleus. The ciliated band remains in the top 

 of the egg throughout the free nuclear stages of the embryo, and 

 sometimes can be distinguished still later. The cilia become indis- 

 tinguishable from the protoplasm of the egg, as if they actually be- 

 come a part of the egg protoplasm; but the dense band, from which 

 they arise, seems solid as long as it can be recognized. 



The behavior of the chromatin, from the entrance of the sperm 

 up to its contact with the egg nucleus, has not been satisfactorily de- 

 scribed in any gymnosperm. Both nuclei are filled with a substance 

 which stains deeply with iron haematoxylin, but most of that sub- 

 stance is certainly not chromatin (fig. 146). Strasburger called it 

 mctaplasm, because he did not regard it as chromatin or as proto- 

 plasm. Even after the sperm nucleus begins to enter the egg nucleus 

 the metaplasm is conspicuous, and the chromatin does not seem to 

 be recognizable (fig. 148). 



The term "fertilization" is used rather loosely and perhaps it is 

 better not to attempt to define it too closely. Any stage with the 

 sperm inside the egg is likely to be called fertilization, and any stage 

 with the two nuclei in contact passes for fertilization. Details are 

 more thoroughly worked out in Coniferales, and so the subject will 

 be treated again, especially in Pinus, Abies, and Jiinipcnis. 



