1 6 Lawson.— The Gametophytes , Archegonia , Fertilization , 
presence of but a single neck-cell in Sequoia sempervirens , but this error has 
recently been corrected by Arnoldi (1900-1), who has found two. It was 
noticeable in examining my preparation that the two neck-cells were not 
always seen in longitudinal sections, but in cross-sections they were very 
distinctly made out. The neck-cells are not only to be distinguished 
by their position and shape, but their contents differ from those of other 
prothallial cells. The cytoplasm is devoid of large vacuoles, and, being 
highly dense and granular, stains more readily with the orange G. than 
do the other cells. 
My observations agree with those of Arnoldi (1901), both in regard to 
distribution of the archegonia over the upper half of the prothallium and 
that two is the typical number of neck-cells. I have, however, found four 
distinct neck-cells in a considerable number of archegonia (Fig. 24). This 
larger number is, however, exceptional. A somewhat similar variation in 
the number of neck-cells has been reported by Murrill (1900) for Tsuga , and 
according to Coker (1901) the number of cells in the neck of the arche- 
gonium in Podocarpus may vary from two to twenty-five. 
It was interesting to observe the position that many of the archegonia 
take in relation to the pollen-tubes. Long before the archegonia are formed, 
the pollen-tubes have grown down and their courses are well established, so 
that their growth is not directed toward the archegonia. On the other 
hand, the growth of the archegonia is invariably directed towards one or the 
other of the pollen-tubes. It has been pointed out (p. 6 ) that the course of 
the pollen-tube varies considerably. Some may grow down alongside the 
prothallium, others are partially surrounded by prothallial tissue, and others 
completely surrounded. In every case there were found numbers of arche- 
gonia pointing towards one or the other of the tubes, and their necks in 
contact with the tube-wall (Fig. 27). 
For some time after the neck-cells have been organized, the central cell 
is completely filled with a very dense granular cytoplasm, in the centre of 
which is suspended a very large nucleus. The next step in the develop- 
ment of the egg-cell is important and interesting, because it bears directly 
on the question of the general occurrence of the ventral canal-cell in the 
Conifers. Arnoldi (1900), in his careful investigations, failed to find any 
vestige of such a cell in Sequoia. He also denies its existence in Crypto - 
meria> Cunninghamia , and Taxodium . On the other hand, the ventral 
canal-cell or nucleus has been found by Strasburger (1879) and Belajeff 
(1893) in Juniperus ; by Blackman (1898), Chamberlain (1899), and Fer- 
guson (1901) in Pinus ; by Coker (1900-2) in Taxodium and Podocarpus ; 
by Murrill (1900) in Tsuga ; and by Land (1902) in Thuja. In Juniperus , 
Pinus , and Tsuga the spindle dividing the central nucleus into the egg and 
ventral nuclei has been described and figured, so that there can be little, 
doubt of its presence in these forms at least. 
