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the Grain of Wheat ( Triticum vulgar i). 
Below this is the ovum, and in the immediate neighbourhood is a crescent- 
shaped structure, presumably the tip of the pollen-tube, which shows a few 
well-marked, darkly-staining bodies. Embedded in the nucleus of the 
ovum, just below the tip of the pollen tube, is an irregular- shaped mass 
distinguished in the section by its darker colour, which is probably the 
generative nucleus that has not yet quite lost its entity. The ovum with its 
nucleus and cytoplasm is bounded by a delicate membrane, a further 
indication that fertilization has occurred. As Cannon (7) also points out, 
Koernicke (8) does not mention a division of the generative nucleus in the 
pollen grain of wheat, and this would be an apparent exception to the 
statement by Strassburger (’84) that the division of the generative nucleus 
is a constant character of the grasses. If this were really the case, then it 
would preclude all possibility of double fertilization occurring in Triticum , 
though it has been demonstrated by Guignard (9) in Zea mais , which 
possesses two generative nuclei. Golinski (10), on the contrary, figures two 
generative nuclei in the pollen grain of wheat, and describes them as being 
elongated and curved and embedded in a special protoplasm, stating that 
they are not unlike the Antherozoids of Ferns and Characeae in appearance. 
In the ovule under consideration dense cytoplasm appears on the other 
side of the embryo-sac, in which are embedded two large nuclei, the result 
of the first division of the definitive nucleus, if we may assume that the 
polar nuclei have already fused. According to Golinski, the two polar 
nuclei are at first in close contact with the ovum : before fertilization, 
however, they pass down into the vicinity of the antipodal cells, after which 
the ovum is ready to be fertilized. Apparently the polar nuclei fuse to 
form the definitive nucleus just at the time of fertilization, so it is probable 
that the two nuclei in question are really the two first endosperm nuclei 
and not the unfused polar nuclei. The fusion and subsequent division 
evidently take place very rapidly. Guignard (9) found in maize that the 
fusion of polar nuclei and the incorporation of the generative nucleus with 
them takes place in such a short space of time that the phenomenon can 
very rarely be observed. 
The antipodal cells at this stage are still well in evidence, but show 
traces of incipient disorganization. In Triticum , as in many of the 
Gramineae, the antipodals are numerous, forming a regular tissue in the 
embryo-sac adjacent to the placenta. Koernicke (8) indicates the presence 
of thirty-six antipodals in this case, while Westermaier (11) gives a full 
account of the literature relating to these cells in the grasses. 
The indications are that fertilization normally occurs between one and 
two days after pollination, as most of the grains taken on the second day 
after are rather more advanced than the one described. In these, part of 
the cytoplasm is massed at the micropylar end about the ovum, and the 
rest, while still remaining in connexion, is gathered round the periphery of 
