1908] _ KILDAHL—PHYLLOCLADUS ALPINUS 341 
' Hallii Burtincame (4) finds two prothallial cells, both of which 
divide and form a tissue, consisting generally of six cells; a similar 
condition was found in Dacrydium by Miss Youne (16). Two more 
divisions follow, so that the mature spore commonly contains four 
free nuclei—prothallial, tube, stalk, and body nuclei. 
On November 1 the four-nucleate microspores are mostly found 
lodged on top of the nucellus (fig. 15); how much earlier they reach it 
and how long they remain there is not known, as no material previous 
to this date was available. In exceptional instances pollen tubes had 
been formed and had penetrated the nucellus (fig. 18); but at this 
date the tube contained only the four nuclei of the mature spore. On 
December 11 the nucellus was in most cases entirely honeycombed 
with pollen tubes, and very much disintegrated (jig. 19). The pollen 
tubes do not pass deviously through the nucellus to any great extent, 
hor branch, but pass almost in a straight line to the embryo sac. As 
Many as fifteen tubes were found in one ovule (fig. 19). 
_ Before the pollen tube enters the embryo sac the body cell divides 
into two equal and optically similar male cells; it was impossible 
'o observe this division, but it takes place some time after the tube 
has penetrated the nucellus and before it enters the embryo sac (figs. 
20, 31b). The entire contents of the pollen tube (five naked nuclei) 
enter the egg (fig. 20). ARNOLDI (1) also finds that in Cephalotaxus 
the contents of the pollen tube are emptied into the embryo sac, the 
contents in this case, however, consisting of only four nuclei; a similar 
Condition has been found in Pinus, where nearly the whole of the 
“ontents of the tube is emptied into the cytoplasm of the egg (COULTER 
and CHAMBERLAIN 10, and FERGUSON 12); according to COKER (8) 
this may also take place in Taxodium (8) and in Podocarpus (7); 
and Courter and Lanp (9) report it for Torreya taxijolia. In 
Ctyptomeria Lawson (16) finds that only one male cell enters the 
archegonium; and JAGER (13) reports the same in Taxus 
In Phyllocladus it is not uncommon to find the entire contents of 
Pollen tubes within the embryo sac after fertilization has taken place, 
and even after the eight-nucleate proembryo stage (fig. 30); this 0 
"= doubt due to the anusial open condition of the archegonia, the 
Sreatly disintegrated nucellus (which seems to be of a very muci- 
us Consistency), and the large number of pollen tubes. 
