\4: Miyake, The development of the gametophytes etc. 



the tip, and right below it. is one lavgc vacuole occupying the 

 Center of the egg (figs. 84 — 87). The structure of the egg-nucleus 

 does not seem to differ niuch from that of the other Conifers. It 

 contains a more or less interrupted reticuluni, which appears sonie- 

 what granulär and niay be composed of an irregulär network of 

 linin in which chromatic granules are imbedded (figs. 84-86, 

 88—90, 112). 



The cytoplasm of the egg presents a finely granulär appearance 

 and contains no such bodies as can be compared with the proteid- 

 vacuoles of the Abietineae. Only some more or less deeply-staining 

 granules are often found scattered in the cytoplasm (figs. 84 — 86). 



Fertilization. 



Fertilization seems to take place one or two days after the 

 cutting off of the ventral canal-nucleus and immediately after the egg- 

 nucleus reaches its mature size. The date varies by season and 

 locality. It differs also even in the same tree. In my material, 

 most of the fusing nuclei were found between July 3 and 5. 

 Generally speaking, we may say that in the niiddle part of Japan, 

 the fertilization of Cunninghamia sinensis occurs during the first 

 week of July, i. e., about three months after pollination. 



As was stated before, the pollen-tube reaches the depression, 

 the archegonial Chamber, above the archegonial complex at the 

 end of June. The division of the generative cell, which is situated 

 at the tip of the tube, seems to take place about the same time 

 as that of the central cell of the archegonium. The two sperm- 

 cells, forraed as the result of the division, become soraewhat en- 

 larged and filled with starch, as was already described. Now the 

 sperm-cells are ready for fertilization, and the stalk- and tube- 

 nuclei are found more or less disorganizing right below them 

 (figs. 35, 87). 



Only one sperm-cell enters each archegonium. No case was 

 found in which two sperm-cells entered into the same egg as it 

 appears sometimes to be the case with Taxndin})i (Coker, 1903). 

 The sperm-cell advances toward the egg-nucleus, aud its nucleus 

 soon comes in contact with the egg-nucleus. The sperm-nucleus 

 now flattens itself against the egg-nucleus (figs. 88 — 90). The 

 diameter of the sperm-nucleus, before entering into the egg, is 

 about half of the egg-nucleus (figs. 35, 90, 107, 112). The former 

 seems to enlarge somewhat after entering the egg, and at the time 

 of conjugation, it approaches the egg-nucleus in size. though some- 

 what smaller than the latter (figs. 88-90). A similar enlarging 

 of the sperm-nucleus in the egg was also described by Ooker 

 (1903) in Taxodiuin and by Lawson (1904b) in Crijpiomcria. 



The fusing nuclei retain their identity for sometime, the two 

 nuclei being separated by a membrane. They are surrounded by 

 a dense sheath of starch-granules (figs. 89, 90, 113). There is no 

 doubt that the greater part of the substance of the sheath is de- 

 rived from the sperm-cell. A similar starch-sheath was observed 

 in Taxodiuni (Coker, 1903) and Crypiomeria (Lawson, 1904b). 



