142 BOTANICAL GAZETTE [AUGUST 
they are derived from an initial cell cut off from the mother-cell of 
the oosphere. It would seem from the recent observations of two 
egg cells in the archegonium of Mnium and of Polytrichum that the 
neck canal cells are potential egg cells, and as such argue for Gayet’s 
theory that the egg cell and neck canal cells have a common origin.— 
Mary C. Buss, Wellesley College. 
POLYEMBRYONY IN GINKGO. 
In the BoraNnicaL GAZETTE 34:64, July 1902, I published a short 
note on the polyembryony of Ginkgo. Since polyembryony is of rather 
common occurrence among the gymnosperms, its frequency in Ginkgo 
becomes a point of some interest. Through the kindness of Dr. George 
T. Moore and Mr. Carl Kellerman, of the Department of Agriculture, 
I have secured a number of seeds of the Ginkgo. A careful examination 
of two hundred specimens give the following results: 12 per cent. were 
without embryos, while 2 per cent. showed two small but well-formed 
embryos in each seed. In the cases of polyembryony the embryos 
averaged about one-third the length of the single embryos. With one 
exception, the double embryos were approximately the same length; in 
this case one embryo was about twice the length of its fellow. The 
single embryos showed great variation in length, but the short ones 
were always thicker than the long ones. One embryo had three well- 
developed cotyledons. — MeL. T. Cook, De Pauw University, Green- 
castle, Ind. 
