432 Lawson . — The Gametophytes , Fertilization and 
jacket-cells and archegonial initials, and suggested that the jacket-cells were 
sterile archegonia. The fact that the jacket-cells are multinucleate in 
Cryptomeria does not argue against this view, but rather strengthens it. 
If the jacket-cells are archegonial initials morphologically, and their 
generative functions changed to one of nourishing, we ought not to expect 
nuclear activity to be entirely suppressed. From this point of view, I 
regard the various nuclei in the jacket-cell as representing the abortive 
nuclei of the egg, ventral canal-cell and neck-cells. 
In this connexion, it is interesting to note that in Sequoia, where 
the archegonia are very numerous, the jacket-cells are less highly dif- 
ferentiated ; and in forms like Pinus , where the archegonia are very few, the 
jacket-cells become very highly specialized as nourishing cells, and even 
have (according to Goroschankin, ’83) a direct communication with the 
cytoplasm of the central cell. 
Fertilization. 
We have already described how the pollen-tube grows directly down- 
ward through the tissue at the apex of the nucellus until it reaches the tip 
of the prothallium. There may be as many as four or five pollen-tubes, and 
their ends reach the depression above the archegonium-complex some little 
time before the archegonia are completely organized. The tubes all grow 
towards this common point, and when they reach the apex of the pro- 
thallium there may be as many as ten male cells situated immediately 
outside the neck-cells. Fertilization is therefore very easily accomplished. 
In many Conifers the process of fertilization becomes very much 
complicated by the entrance of other pollen-tube structures than the male 
cell into the archegonium. In Pinus nearly the whole of the contents 
of the pollen-tube passes into the archegonium (Goroschankin, ’83 ; 
Dixon, ’94 ; Blackman, ’98 ; Ferguson, ’01 ; Coulter and Chamberlain, ’01) ; 
a similar condition has been found in Taxodium (Coker, ’03 ; Cephalotaxus 
(Arnoldi, ’00), and in Pice a excelsa (Miyake, ’03). In Picea vulgaris , 
Strasburger (’84) reports that two male cells enter one archegonium. In 
Thuja , Land (’02) finds that the tube- and stalk-nuclei may occasionally 
enter the archegonium, but they more generally remain outside and become 
disorganized in the cavity above the archegonium-complex. From these 
recorded observations it appears that the fertilization of many Conifers 
at the time of fusion of the male and female nuclei becomes very much 
complicated by the presence of other pollen-tube structures in the arche- 
gonium which take no essential part in actual fertilization. In Sequoia 
(Lawson, ’04), however, quite a different and much more simple process 
prevails. Here only the nucleus and a very small amount of cytoplasm of 
the male cell enters the archegonium, so that at the time of fusion only the 
