288 BOTANICAL GAZETTE [APRIL 
to be the fertilization nucleus. At that time BELAJEFF (6) showed 
that in Taxus baccata the larger cell is not the generative cell; but 
that the small cell divides in the tube and one of the derivatives 
becomes the generative cell. 
In 1892 STRASBURGER (1) described Ginkgo biloba as having two 
prothallial cells, representing a vegetative prothallus, and an 
antheridial cell, which are successively cut off from the pollen 
cell; the antheridial cell divides into stalk and body; the latter 
produces the sperms. The large pollen nucleus, because of its 
foremost position in the tube, was called the tube nucleus. The 
general conception of origin and function is the same today. It is 
not surprising, however, that, with such a variety of types, different 
investigators have since used different terms to designate similar 
cells. 
The system of nomenclature to be used in this account has been 
made necessary by the nature of the gametophytic development. 
The primary cell (P) is regarded as retaining its identity, just as 
an apical cell. In the pollen tube stages it is represented by the 
tube nucleus. The successive divisions of the primary nucleus are 
known as primary divisions; the cells cut off are called, tentatively, 
the first, second, or third primary derivatives (a’, a”, a’”’ in figs.). 
Divisions of the latter cells are called secondary. The cell which 
later divides to form male nuclei is termed spermatogenous (s in 
figs.); the sister non-functioning cell is the sterile cell (s¢ in figs.). 
The mother cell of a spermatogenous and a sterile cell is called an 
antheridial cell. 
Development of the male gametophyte 
The first primary division is variable; the cell wall may cut 
off a lenticular polar cell (fig. 7); it may be oriented at right angles 
to the longitudinal axis, cutting off approximately one-third of 
the protoplasmic mass (figs. 6, 33, 37, 53); it may be in the plane 
of the vertical axis, in which case two nearly equal cells result 
(figs. 2, 10, 1, 13, 31, 32); it is often inclined (figs. 28, 29)3 and 
occasionally no dividing wall is formed, the two resulting nuclei 
being then free in the cytoplasmic mass (figs. 8, 9, 12). The further 
development of the resulting cells is largely determined by the 
