THE HIGHER CRYPTOGAMIA. 411 



cells often divided transversely, so that the rosette consisted 

 of eight cells lying in two planes. Pinus canadensis and 

 Picca L. are remarkable exceptions. Here the one cell 

 which covers the top of the corpuscnla does not divide by 

 longitudinal septa crossing one another, but by repeated 

 transverse septa (PL LXII, figs. 1, 2). It thus keeps pace 

 with the multiplication of the cells of the top of the endo- 

 sperm, which multiplication in the other Abietinese and in 

 Juniperus continues after the formation of the corpuscula, 

 whilst in the above species the double pairs of cells which 

 cover the upper arch of the corpuscula are sunk in depres- 

 sions of the upper side of the endosperm, over which the 

 primary membrane of the embryo-sac extends. In Juni- 

 perus, Thuja, and Cupressus the top cells of all the corpus- 

 cula, with rare exceptions, are closely crowded together at 

 the base of a wide depression of the top of the endosperm 

 (PL LXV, figs. 2, 9). The upper end of the endosperm of 

 Pinus exhibits as many funnel-shaped depressions as there 

 are corpuscula ; each of these short passages leads to a 

 single corpusculum. In like manner, in Juniperus, Thuja, 

 and Cupressus, the parenchyma of the endosperm grows 

 over the covering cells of the corpuscula. At the top of 

 the endosperm there is found a rather deep depression 

 whose base is occupied by the closely-crowded four-celled 

 rosettes of the elongated corpuscula, which latter are in 

 contact with one another. 



The cells of the endosperm which adjoin the corpusculum 

 on the sides and below, divide repeatedly by septa at right 

 angles to the surface of the latter. A layer is thus formed 

 which surrounds the corpusculum, and consists of small 

 cells filled with granular mucilage. This layer is very 

 striking in the Abietinese. 



In Pinus sylvestris and austriaca the number of corpus- 

 cula is from three to five ; in Abies balsamea and pectinata 

 usually three ; in Pinus canadensis very regularly four (rarely 

 five) ; in Taxus baccata and Juniperus from five to eight. 



The primary nucleus of the cell which becomes the cor- 

 pusculum lasts for some time ; in Pinus sylvestris (PL LX, 

 figs. 5, 6) until the corpusculum has attained half its full 



