138 MARGARET C. FERGUSON 



cell, since it lies in the cytoplasm of a cell which supplies the 

 most favorable medium for growth found in the plant. Not the 

 slightest evidence has been observed during this research that 

 the nucleus of the ventral canal-cell ever divides or that it ever 

 conjugates either with the egg-nucleus or with the smaller 

 sperm-nucleus. The fact that this nucleus enlarges when fed 

 by the cytoplasm of the egg does not seem to me conclusive 

 evidence that it has been " organized as an egg," as stated by 

 Coulter and Chamberlain ('01). The tube-nucleus and the 

 smaller sperm-nucleus often enlarge after their entrance into 

 the egg but, surely, they are not thereby changed into eggs. 



The fragmentation of the egg-nucleus has been observed sev- 

 eral times and is illustrated in fig. 270. The ventral canal-cell 

 can still be seen just above the egg. Such fragmentation of the 

 egg-nucleus is not rare in the Gymnosperms having been re- 

 ported by various writers. 



In one instance one of the two segementation-nuclei was 

 found to have divided while the other remained undivided. The 

 undivided nucleus had increased much in size and contained 

 seven large, granular spheres distributed on an achromatic re- 

 ticulum. The nucleus is evidently in a state of disintegration 

 and these spheres probably represent granular masses of chro- 

 matin (fig. 274). 



A Peculiar Method of Conjugation. Of all the irregular or 

 abnormal developments observed that illustrated in fig. 275 is, 

 to me, the most interesting. A pollen-tube has conjugated with 

 an egg, not through the normal passage formed by the neck- 

 cells, but has forced its way through the sheath-cells at one 

 side of the archegonium. Impregnation has evidently followed 

 and division has taken place as usual, four nuclei of the pro- 

 embryo having been formed. 



The fifth large nucleus shown within the egg is doubtless the 

 smaller sperm-nucleus. The open space separating the upper 

 part of the prothallium from the nucellar cap has evidently not 

 arisen as a result of shrinkage during fixation. The pollen- 

 tube unable to span the opening has turned aside and finding a 

 point at which the endosperm and nucellus were in contact it 

 has entered the prothallium and made its way along the side 



