142 K.Miyake, Contribut. to the Fertiliz. and Enibryogeny of Abies balsamea. 



of cells, with foui' cells in each tier. Sheatli cells of tlie nearlj^ 

 matiire archegonium often attemijt to divide and sliow cliromosonies 

 clear and distinct; tlie numl)er of the latter was found to be twelve 

 or approximately twelve. 



2. The nucleus of the central -cell is not located so close to 

 the neck -cells as in Pinus and Picea, but is somewhat separated 

 from them as in Tsuga. It has a prominent niicleolus, and shows 

 an accunuilation of chromatic substance near the centre of the 

 nuclear cavity before it begins to divide. In the division, spindle- 

 fibres arise froni both places outside of the nucleus, the lower pole 

 being much more prominent compared with the upper one. 



3. When the ventral canal-cell is formed, its nucleus is almost 

 equal to the egg-nucleus and for some time shows somewhat siniilar 

 stages of development. The nucleus enlarges several times and soon 

 fills a larger part of the cell. The ventral canal-cell usually per- 

 sists until the time of fertilization , and its nucleus is often foimd 

 near the apex of the ^g^, after the entrance of the pollen-tube 

 Contents. 



4. The mature egg -nucleus situated at the centre of the egg 

 is more oi' less oval or eUiptical, and its average diameters are 

 100 — 120 ^ by 140—160 //. The proteid-vacuoles, wliich iirst appear 

 in the mature central - cell , become numerous and prominent after 

 the formation of the ventral canal-cell. About the time of fertili- 

 zation the egg-cytoplasm presents a more coarsely granulär structure. 



5. Among several abnormal archegonia observed, those without 

 neck-cells and the double ones (one archegonium lying above the 

 other) were often observed. In one case a double archegonium was 

 found without neck-cells, and in the upper archegonium two egg- 

 nuclei were present. Another interesting monstrosity was an arche- 

 gonium with two egg -nuclei and two ventral canal-cells, having a 

 Single neck above one of the ventral canal-cells. 



6. x^t the time of fertilization, nearly the whole Contents of 

 the lower part of the pollen-tube, includüig the two sperm- nuclei 

 surrounded by their common cytoplasm, the stalk-cell and the tube- 

 nucleus are discharged into the Qgg. The larger sperm -nucleus 

 slips from the sperm-cytoplasm and moves dii^ectly towards the egg- 

 nucleus. The sperm-nucleus after Coming into contact with the %gg- 

 nucleus, gradually imbeds itself in the side of the latter, but does 

 not penetrate its membrame. The later changes in the conjugating 

 nuclei have not been foUowed. 



7. The fertilized nucleus soon forms four free nuclei by two 

 successive divisions. The four nuclei soon move down to the base 

 of the Qgg, and divide there simultaneously ; after the eight nuclei 

 are completely formed, walls are laid down between them. 



8. The second sperm-nucleus, tube- nucleus and stalk-nucleus, 

 wliich are left at the upper part of the Qgg divide or attempt to 

 divide betöre they disintegrate. Their division figui^es are, however, 

 more or less abnormal or abortive. 



9. An interesting monstrosity which miglit be interpreted as 

 a case of double fertilization, — the fertilization of one of the 

 second segmentation-nucleus by the second sperm-nucleus, was found 

 in one preparation. 



