4 6 BOTANICAL GAZETTE [july 



region contains a tangle of long, tortuous, and branching suspensors 

 (figs. 6, 7), which are difficult to trace. During the formation of a 

 suspensor by a fertilized egg, free nuclear division occurs, resulting 

 in a few nuclei (four in fig. 7) distributed along the suspensor. Usually 

 between these nuclei transverse walls are formed by the development 

 of a cleavage plate from the wall of the suspensor. A cell at the 

 tip of the suspensor is cut off in the same way, and contains one of 

 the free nuclei, which becomes associated with numerous starch 

 grains (fig. 7). 



In this terminal embryonal cell free nuclear division continues 

 (figs. 8, 9, 10), accompanied by cleavage walls, until a multicellular 

 embryo is formed. In figs. 9 and 10 it will be observed that this 

 cleavage apparently continues until uninucleate cells are produced; 

 and in our material this stage is reached first by a group of cells on 

 one side of the embryo. It could not be determined whether this 

 group holds any relation to a body region or not. 



It has been supposed that in the embryogeny of Gnetum the 

 preliminary stage of free nuclear division, common to other gymno- 

 sperms, had been eliminated; and that the first nuclear division was 

 accompanied by wall formation, as in angiosperms. In Gnetum 

 Gnemon, however, free nuclear division not only characterizes the 

 proembryo, but also the early stages of the embryo. The case may 

 be compared to that of Ephedra, 5 in which free nuclear division 

 within the fertilized egg results in eight independent proembryonal 

 cells, each of which continues free nuclear division and develops as 

 a suspensor, which by a cleavage wall cuts off the terminal embryonal 

 cell. In Gnetum the suspensor is formed by the fertilized egg instead 

 of by a proembryonal cell, but the number of free nuclei formed by 

 the egg in each case is approximately the same. 



INTEGUMENTS 



The mature seed of Gnetum Gnemon gives an opportunity to 

 compare the integument and testa with those of other gymnosperms. 

 Fig. 6a shows the seed slightly stalked within the so-called " perianth," 

 which is fleshy. Two integuments are evident, and they develop in 



s Land, W. J. G., Fertilization and embryogeny in Ephedra trijiirca. Bot. 

 Gazette 44:273-292. pis. 20-22. 1907. 



