Miyake, The development of the gametophytes etc. 13 
Enveloping the archegonial complex, there is a single layer 
of sheath- or jacket-cells. At first they are poor in contents and 
can scarcely be distinguisbed from the neighboring cells of the 
prothallium, but later on the cells become rieh in cjToplasm and 
the nuclei more prominent (figs. 69. 70, 72, 87). In the full-grown 
archegonia, many of the jacket-cells are binucleate. The same 
was found to be the case with Libocedrus by Lawson (1907). 
Coker (1903) also mentions that the jacket-cells of the mature 
archegonia in Taxodium generally contain two nnclei. In Cryp¬ 
tomeria, according to Lawson (1904b), nearly all of them are 
multinucleate. It is to be noticed that the jacket-cells near the 
apex of the archegonia are generally poor in contents and resembles 
closely the adjacent prothallial cells. Judging from the figures of 
Lawson (1904b, figs. 39, 40) this seems to be true also in Cryp¬ 
tomeria. 
As the central cell of the archegonium reaches its full size, 
the cytoplasm becomes densely granulär and most of the smaller 
vacuoles disappear, leaving usually one big vacuole at the center. 
The nucleus now undergoes division. The early stages of the 
division were not found. Yarious stages of the karyokinetic spindle 
are shown in figs. 77—81. All of the nnclei of a single arche¬ 
gonial complex seem to divide almost simultaneonsly. Of the two 
nuclei thus formed, the upper one, the ventral canal-nucleus, 
usually soon degenerates and its remnant may, for a time, be seen 
as deeply staining body at the tip of the egg (fig. 82). 
Arnoldi (1900) denies the formation of a ventral canal- 
nucleus in Sequoia, Taxodium, Cryptomeria and Cunninghamia. 
His conclusion was not confirmed by the later researches of Coker 
(1903) in Taxodium and those of Lawson (1904) in Sequoia and 
Cryptomeria. Coker has studied carefully the division in the 
ventral canal-nucleus in Taxodium. Although Lawson did not 
observe any division-figure in the two genera above mentioned, he 
seems to have enough evidence for the existence of such division. 
My observations now put the formation of the ventral canal-nucleus 
in Cunninghamia beyond doubt, A doubt was also expressed by 
Arnoldi (1899b) as to the presence of a ventral canal-nucleus in 
the Cupressineae\ but the recent Investigators (Land, 1902; Noren, 
1907; Lawson, 1907) all agree in the existence of such nucleus 
in that group. Only other species of the Coniferae , in which the 
absence of a ventral canal-nucleus was reported, is Torreya taxi- 
folict (Co ult er and Land, 1905). It was, however, found in 
Torreya californica by Miss Robertson (1904), and it is not im¬ 
probable that the later researches may reveal the existence ofthe 
nucleus in the former species. It seems, therefore, that the for¬ 
mation of the ventral canal-cell or nucleus is a rule among the 
Coniferae and also among the rest of the Gymnosperms. 
The lower of the two nuclei, resulted from the division of 
the central nucleus, the egg-nucleus, immediately begins to enlarge, 
and at the same time moves downward (figs. 82, 83). In the 
mature egg, the nucleus is usually found about one third below 
