408 HOFMEISTER, ON 



triplication recommences in the cells of the ovule, with the 

 exception of the upper portion of it which has been tra- 

 versed by the pollen-tnbes and which remains stationary ; 

 the ovule grows from one third of a line to two lines and 

 a half. 



In the middle of May a simple layer of cells begins to 

 spread itself on the inner wall of the embryo-sac (PI. LX, 

 fig. 2). The side-walls of these cells do not yet touch one 

 another at all points (PL LX, fig. 2 b ) ; if the embryo-sac is 

 ruptured by gradually increased pressure, the cells within 

 it and those also which are spread over its wall are driven 

 out through the fissure in the form of spherical vesicles 

 (PL LX, fig. 3). The firm adhesion inter se of the above 

 cells does not take place until after several layers of them 

 have been formed (PL LX, fig. 4). The cell-multiplication 

 at the same time goes on continually, both in the free cells 

 of the centre, and in those forming the parenchymatal 

 mass of the periphery. Thus at last there is again formed 

 an endosperm entirely filling the inner cavity of the 

 embryo-sac, a body far longer in its circumference and 

 composed of a far greater number of cells than the one 

 which existed at the commencement of the winter rest. The 

 development of the endosperm of Juniperus much re- 

 sembles that of the species of Pinus whose seeds take two 

 years to ripen. In the lower part of the nucleus before 

 the shedding of the pollen there is found a cell surrounded 

 by concentrical layers of smaller cells: this cell is the 

 embryo-sac. It becomes filled with a few cells (PL LXIV, 

 fig. 5), shortly after those pollen-grains which have reached 

 the nucleus have begun to emit tubes. In this condition 

 the ovule remains through the first summer and winter. 

 At the commencement of the next vegetative period the 

 ovule and embryo- sac increase rapidly and remarkably in 

 size, and the primordial utricles of the cells which fill the 

 embryo-sac become individualised. By active multiplication 

 of these primordial cells, numerous cells are produced 

 floating freely in the fluid contents of the embryo-sac. They 

 soon * clothe the inner wall of the embryo-sac in the form 

 of a compound cellular layer (PL LXIV, fig. 6); by division 



* At the beginning of May in the second year. 



