420 Lawson. — The Gametophytes, Fertilization and 
membrane between the nuclei has disappeared, and the cytoplasm 
surrounding the latter is very granular but uniform throughout. 
In the Cycads, Ginkgo , Pinus and Podocarpus , one or more vestigial 
vegetative ceils of the gametophyte have been observed in the pollen-grain. 
As far as I have been able to make out, no such cells are organized in 
Cryptomeria. From daily collections made during the entire period of the 
development of the male gametophyte, close observation failed to reveal 
any trace of a vegetative cell or of a nucleus representing such a cell. In 
this respect the pollen-grain of Cryptomeria resembles that of Thuja (Land, 
’01), Taxodium (Coker, ’03), and Sequoia (Lawson, ’04). Not only at 
the time of pollination, but for about three weeks after the microspores 
have been received at the apex of the nucellus, there are but two nuclei 
present in each spore. The later history of the larger of these proved 
it to be the tube-nucleus, and the smaller one, no doubt, represents the 
generative cell. 
During the latter half of February, when the female flowers first 
become visible, the microsporangia open and the pollen is liberated. For 
about two weeks the branches of the trees are quite yellow from the great 
quantities of pollen that have fallen on them. As the female flowers are 
open at this time, it is practically impossible for them to escape the 
reception of the pollen. Longitudinal sections of the female flower taken 
at this stage showed the integument of the ovule extending slightly above 
the level of the apex of the nucellus, leaving the micropyle open. From 
three to eight pollen-grains were always found deposited on the apex of 
the nucellus. As in Sequoia , the pollen-grains retain this position for about 
three or four weeks without further changes. The upper portion of the 
integument grows over the pollen-grains and closes the micropyle in very 
much the same manner as it does in Sequoia. The epidermal and sub- 
epidermal cells lining the micropyle lengthen towards the centre of the 
latter until they finally meet and the micropyle is closed. Fig. 9 shows the 
micropyle nearly closed. 
Very soon after the casting off of the thick outer wall of the pollen- 
grain, the tube pushes out and immediately penetrates the tissue at the 
apex of the nucellus. It will be remembered that in Sequoia (Shaw, ’96 ; 
Arnoldi, ’01 ; Lawson, ’04), many of the tubes do not penetrate the 
nucellar tissue immediately, but grow down between the integument and 
the nucellus. This is clearly not the case in Cryptomeria. Fig. 7 shows 
at least four tubes penetrating the nucellar tissue at the apex. An 
examination of hundreds of tubes failed to reveal any indication of 
branching. The tubes grow directly downward towards the developing 
female prothallium. Fig. 8 shows a typical tube ; the tube- and stalk- 
nuclei and the body-cell are at the tip, and are about to be discharged 
into the depression above the archegonium-complex. In the course of 
