40 DR. MARGARET BENSON, MISS E. SANDAY, AND MISS E. BERRIDGE ON 
'The spur is very well seen in the preparation from which fig. 6 is taken, and several 
other cases have been found. A strand of protoplasm, probably marking the path 
of the generative nucleus, usually connects the spur with the polar nuclei. Several 
preparations show a generative nucleus in contact with the definitive nucleus, while 
in one it is in the act of travelling up the cecum, and lies midway between the 
spur and the definitive nucleus (PI. 6. fig. 3, g.n.) In this latter case it is slightly 
crescentic, and stains deeply and uniformly ; it resembles those still enclosed in the tube, 
drawn in fig. 4, but is about twice as large. 
One section of a series cut in 1905, stained with the triple stain, contains a very 
clearly defined generative nucleus. The complete section of the two embryo-sacs of the 
ovule in which it occurs is represented somewhat diagrammatically in fig. 6. The 
pollen-tube runs up the side of one sac and throws out a spur just opposite the definitive 
nucleus. In fig. 6@ the latter is seen under higher magnification with the generative 
nucleus beside it; this is elongated and somewhat flattened, twisted on itself, but not 
closely coiled. One end rests upon the definitive nucleus, in which the fusion of 
the polars is quite complete; this appears to take place, however, only just before 
fertilization, as nuts gathered the previous day almost invariably show the two polars 
in contact but still quite distinct. Another clear example of a male gamete about to 
fuse with the recentiy formed definitive nucleus was found; in this case the male 
gamete is elongated in shape, but does not appear to be twisted or coiled. A third case 
was unfortunately somewhat crushed, but it is similar in form to that in fig. 6 a. 
Several preparations show the definitive and generative nuclei closely associated and 
more or less fused together; one such case is represented in fig. 5a. | 
Division of the definitive nucleus follows rapidly after fusion with the generative 
nucleus, and à day or two later a considerable number of endosperm-nuclei may be 
observed against the wall of the embryo-sac. | 
After passing one or, frequently, several definitive nuclei, the pollen-tube makes its 
way into the upper part of the embryo-sac, and arches over the egg which will eventually 
be fertilized. In fig. 10, drawn from a preparation showing the fertilization of the 
egg-cell, only the tip of the pollen-tube appears, running down one side of the egg- —— 
apparatus. Between this tip of the tube and the egg-cell, and applied to one side of 
the latter, is a generative nucleus. It is here seen almost edgeways, and appears to be - 
closely coiled or folded upon itself. A rather ill-defined nucleus is observable within 
the tip of the pollen-tube. This is probably the vegetative nucleus which has begun to 
degenerate. A portion of a synergid is also present, but is not figured. | 
The generative nucleus here seen is of the same size as the two found in contact with 
the definitive nucleus, being about 14 u in length, but is considérably larger than those 
in the tube; an increase in size has often been remarked by workers on other plants 
after the generative nucleus has left the pollen-tube. After fertilization the egg-cell 
Increases in size and definiteness and soon develops a wall. In this condition it rests for : 
some days while endosperm-formation is actively progressing. i 
With respect to the question as to whether the tube contains more than the normal 
number of generative nuclei, we may state that the question is rendered difficult by the 
