ON TnE GERMINATION OF CnAEA. 303 



the succession and arrangement of the cells can no longer he made 

 out. As its cells increase in size, this hody expands considerably, and 

 pushes itself out of the shell. Its superficial cells grow out into roots, 

 or some of them occasionally into accessory pro-embryos. Hence, in 

 somewhat advanced germinating plants several additional roots usually 

 issue from the base of the primary root, near the point whence the 

 principal pro-embryo issues, among which, however, the main root is 

 easily recognised by its larger size. 



Eespecting the further development of the principal pro-embryo, 

 whose rudiment was left as a tube-like prolongation of the apex of 

 the principal pro-embryonic cell, I have simply to confirm Pringsheim's 

 statement that it proceeds in precisely the same manner as in the 

 accessory pro-embryos of every kind. As Pringsheim describes it, the 

 tube, which grows throughout its whole length and slightly enlarges 

 in diameter, is first of all divided at its upper end by a cross partition 

 forming an independent cell, which by further division is changed 

 into a pro-embryonic apex, consisting of 2-6 series of cells. 



The cells of this pro-embryonic apex grow considerably, both in 

 length and breadth, without further division, contain abundant chlo- 

 rophyll, and represent together the apparent disproportionately large 

 leaf, which rises with the whorl and normal stem-bud of the pro- 

 embryo. In the number of cells, of which the pro-embryonic apex is 

 built up, difi'erent species show slight diversities. I found then three- 

 or four-celled in Chara cn7iita,foetida, and fragilis, and Tolypella glorne- 

 rata ; 3-celled in the few specimens available for examination of 

 C. scoparia ; invariably only 2 -celled in Tolypella intricata, Nitella 

 hyalina and capitata. The original tube enlarges out a little imme- 

 diately below the point, and this swollen portion is eventually sepa- 

 rated by a cross partition from the otherwise undivided, usually 

 elongated, lower part of the tube, which contains little chlorophyll. 

 In this inflated cell, on the other hand, two cross-walls are formed in 

 quick succession, separating an upper and lower shallow cell from an 

 intermediate one. The separation of the lower is eff'ected first, and 

 is sometimes found without the upper. Indeed in by far the 

 greater number of cases which came under observation both were 

 present, and therefore the upper follows the lower very rapidly, or 

 perhaps both are often formed at the same time. The intermediate cell 

 does not again divide, but lengthens more or less into a cylindrical chlo- 

 rophyll-holding tube. The other two, after the manner of the nodal cells 

 of the Characece, become points of departure of new ramifications ; they 

 may, therefore, in harmony with our general terminology, be called, 

 respectively, the second and third nodes of the germinating plant, or 

 after their further development, according to Pringsheim's initiative, 

 the lower (r) may be designated root-node, and the upper (s) 

 stem-node. The root-node originates as a shallow disk-like 

 cell, and this shortly divides vertical walls, and thus becomes 

 a many-celled one-storied disk. The first partition halves the 

 cell-cavity, and each of these more or less equal halves is then either 

 again divided by a wall not quite parallel to the first, as Pringsheim 

 denotes, so that the node consists of four narrow cells of similar 

 conformation, or it is divided by a partition cutting the other at nearly 

 right angles (figs. 7 and 8). Even these divisions of the second de- 



