some distance above the antherozoid cells and 
1897] DEVELOPMENT OF THE ANTHEROZOIDS OF ZAMIA 19 
the watery contents of the pollen tube are quickly forced out, 
and the pollen tube immediately shrivels up into a shapeless mass. 
This is probably what happens naturally in the course of fecun- 
dation. The pollen tube evidently grows down until the end is 
forced against the neck cells, when the tube 
bursts, discharging the mature antherozoids and 
the watery contents of the tube which supplies a 
drop of fluid in which the antherozoids can swim. 
I have several times observed the antherozoids 
after they were discharged over the archegonia, 
but studying them in this position is difficult 
and unsatisfactory. For purposes of microscopic 
study the pollen tubes were carefully cut off 
placed in water, but this proved unsatisfactory, 
as the antherozoids soon died and burst, evi- fluence of 10 per 
dently from the difference in density of water cent: sugar solu: 
and the contents of the pollen tube. Solutions |. 
of cane sugar of several strengths were then mediately be- 
tried, and a 10 per cent. solution proved thor- fore fecundation 
oughly satisfactory. By the use of this solution te 
I was able to keep the antherozoids living and same tube about 
moving for a considerable time, ustially from fvemiantes leter; 
thirty to sixty minutes, and in one case two hours eee 
and forty-four minutes When mature pollen ee pier tube: 
tubes are placed in sugar solution the proximal 4, proximal cell; 
cell, protoplasm, etc., can at first be seen to have 2% antherozoids. 
their normal shape, the antherozoid cells usually 
still adhering to each other (fig.5 A). Ina few minutes, how- 
€ver, when the sugar has had time to diffuse into the pollen tube, 
the proximal cell and protoplasm break down into a shapeless 
mass, and the antherozoids, under the stimulation of the sugar 
solution, gradually begin to awaken into life, as it were. The cilia 
begin to move, and the cells round up and slowly pull apart (fig. 
5 8). When swimming free without pressure the antherozoids 
are slightly ovate, nearly round, or compressed spherical (jig. 4). 
