﻿3 6 2 



BOTANICAL GAZETTE 



number of chromosomes as 12. Several preparations show that 

 no wall is formed between the two nuclei, and that the ventral 

 canal nucleus soon disorganizes, while the egg nucleus increases 

 rapidly in size as it moves toward the center of the egg. 



Some irregularities were noted. In two cases there were 4 neck 

 cells instead of 2, in one of the two cases the two original cells having 

 divided longitudinally, and in the other transversely. In several 

 cases the central cell of the archegonium had not continued its 

 development and was no larger than the tissue cells of the game- 

 tophyte, but the two neck cells were as large and turgid as those 

 of a normal archegonium. 



Fertilization 



The archegonial chamber at the time of fertilization is moist, 

 but no droplets of fluid can be seen, even with a 16 mm. objective. 

 On the other hand, the pollen tubes are turgid, and as they dis- 

 charge furnish enough fluid for a limited movement of the sperms. 

 After the nucellus has been removed from the ovule, it is easy to 

 see the sperms swimming in the pollen tube, but practically impos- 

 sible to observe them, under natural conditions, in the archegonial 

 chamber. The entrance of the sperm into the egg is probably 

 effected as already suggested for Dioon edule (12). The liquid dis- 

 charged from the pollen tube is of high osmotic pressure, and con- 

 sequently draws some liquid from the turgid neck cells, and the 

 lowered turgidity of these cells allows a portion of the upper part 

 of the egg to escape, thus forming a vacuole which draws the sperm 

 into the egg. The careful experiments of Miyake (8) have shown 

 that the cycad sperm does not respond to chemotactic stimuli, 

 being indifferent even to the material of the egg. 



It is quite common for more than one sperm to pass through the 

 neck of the archegonium, but rare for more than one to enter the 

 egg itself (figs. 10, 11, 13). In one case 7 extra sperms had passed 

 through the neck; in another case 4; in several cases 3; and in 

 many cases 2 or 1. The apex of the extra sperm is usually directed 

 toward the main body of the egg, and in such cases the sperm 

 becomes more or less imbedded, doubtless on account of the move- 

 ments of the cilia; but when the axis is not directed in this way, 



