FEBRUARY 15, 1901.] 
These cells the writer referred to as the 
first, second and third prothallial cells, in 
the order of their formation. 
During the development of the pollen 
tube and prothallial apparatus in the nucel- 
lar tissue after pollination, the second pro- 
thallial cell crowds out into the third pro- 
thallial cell which meanwhile retains its 
original point of attachment and comes to 
surround the second prothallial cell like a 
root-cap. When the third prothallial cell 
divides to form the stalk cell and central 
cell (Korper cell, generative cell), the spin- 
dle is formed diagonally in the cell, the 
nucleus of the forming stalk cell being 
crowded to one side by the intruding second 
prothallial cell. When the stalk cell is cut 
off by the completion of the division, it ap- 
pears nearly cylindrical and completely 
surrounds the second prothallial cell except 
at the base, where both cells retain their 
original attachment. This same structure 
and development have been found by the 
writer to occur in Ginkgo also, and while in 
Ginkgo the division of the third prothallial 
cell has not been observed, the writer 
thinks there can be no doubt that the de- 
velopment is the same as in Zama. This 
interpretation, it should be added, is totally 
different from that described by Ikeno and 
Hirase as occurring in Cycas and Ginkgo, 
but neither of these investigators observed 
the division of the third prothallial cell. 
During the development of the apical 
end of the pollen tube in the tissue of the 
nucellus, the vegetative nucleus passes into 
the tube and during the growth of the lat- 
ter remains near its apex. When the 
proximal end of the tube (the pollen grain 
end ) begins to grow down toward the arche- 
gonia, shortly preceding fecundation, the 
vegetative nucleus travels back through the 
entire length of the tube, two or three milli- 
meters, and takes position in the proximal 
end of the tube near the central cell. This 
change of position suggests that the nucleus 
SCLENOE. 255 
governs and directs growth, and changes its 
location in the cell in order to be nearest 
to the point of most active growth, a factor 
emphasized by Haberlandt in his ‘ Func- 
tion und Lage des Zellkernes.’ 
Notes on the Spermatozoids of Ginkgo: Ernst 
A. Brssey, Department of Agriculture. 
(By invitation. ) 
In Washington the spermatozoids of 
Ginkgo are developed between August 25th 
and September 10th, as extremes, the most 
favorable time for finding them being 
September Ist to 3d. They are developed 
in the night or early morning. They are 
about 105 x 75-82, in size, with nucleus 
71-75». The nucleolus is 7.5 in diame- 
ter. The cilia are about 15» long. There 
are three turns inthe spiral band which bears 
the cilia. The spermatozoid has no tail 
such as Hirase described, the latter’s obser- 
vation being probably on injured specimens, 
as Fujii has recently pointed out. 
The ciliar motions are the regular tremu- 
lous motions of the cilia and also a series 
of waves passing from the apex to the base 
of the spiral. The body of the spermato- 
zoid is very movable, especially the cilifer- 
ous portion, twisting, bending, elongating 
and contracting very remarkably. At the 
base of the cell, exactly opposite the apex 
of the spiral, there is a trembling motion 
apparently coincident with, and connected 
with the movement of the cilia. Its sig- 
nificance has not been determined. 
Spherites and Sphere Crystals and their Rela- 
tion to Plant Structures; Dr. HENRY KRAE- 
MER, Philadelphia College of Pharmacy. 
On the basis of their physical properties 
the author has grouped the substances 
making up the contents and walls of plant 
cells into (1) the cell liquids or cell fluids ; 
(2) sphere crystals; and (38) spherites. 
The cell liquids include the organized con- 
tents of the cell and a portion of the unor- 
ganized contents as cell sap. The sphere 
