298 Proceedings of Indiana Academy of Science 



surviving in the mature seed. Both were unable to obliterate completely 

 the three smaller embryos by the time the seed matured. 



What it is that enables the successful embryo or embryos to win 

 out in the struggle, assuming that two or more have an equal start, 

 can only be conjectured. 



The writer has conducted a class in the embryology of Gymno- 

 sperms for many years, using chiefly Pinus laricio, and of the numerous 

 pro-embryos in various stages of growth observed, the one which appar- 

 ently had the upper hand seemed to be the one plunged more deeply 

 chalazal-wards in the endosperm, but cases have been observed in which 

 the deepest was not the largest. 



Time and again it has been observed in microtome sections that 

 embryos were entangled among the suspensors, some pointing directly 

 towards the micropyle and growing in that direction. It would seem 

 reasonable to assume that such embryos would be as well nourished 

 as those growing downward into the endosperm. 



For an admirable presentation of polyembryony in Gymnosperms 

 the reader is referred to the following papers by John T. Buchholz: 

 Suspensor and early embryo of Pinus. Bot. Gaz. 66: 185-228, 1918; 

 Polyembryony among Abietineae. Bot. Gaz. 69: 153-167, 1920; Embryo 

 development and polyembryony in relation to the phylogeny of conifers. 

 Amer. Jour. Bot. 7: 125-145, 1920. 



