Studies in the proteaceæ

Summary

This paper is a detailed account of the structure and development of the endosperm and thevermiform appendage.

After fertilization some free endosperm nuclei are formed, and these are distributed in the upper two-thirds of the embryo-sac, with a strong accumulation at the micropylar end. The organization of cellular endosperm begins a little later, and in this only the nuclei in the micropylar end participate. The rest of the embryo-sac becomes zig-zag in its form and develops into a cœnocytic haustorial structure with a strikingly worm-like appearance. This is designated thevermiform appendage which was discovered by the writer. The antipodal cells are seen persisting at this stage and also later.

Thevermiform appendage shows two distinct phases in its growth and development; the first phase is characterized by the cœnocytic nature of theappendage with free endosperm nuclei, and the second by the formation of cross partitions followed later by cell formation to give rise to a secondary endosperm tissue. In mature seeds both theappendage and the endosperm tissue are completely used up by the embryo.

The nature and origin of thevermiform appendage are discussed in the paper.