140 The Significance of Sex. [ Feb. 
plex and highly-organized structure. We can no longer use the 
term protoplasm in its old sense of one definite substance whose 
remarkable properties are due to the great chemical complexity 
of its molecule. 
1. Historical—In the works of Schleiden and Schwann (1838- 
1840), which established the cell-doctrine, the cell was described 
as originating by the activity of the cytod/ast (the nucleus), which 
was itself due to a condensation of granules in the cell-substance 
of the mother-cell. The endogenous origin of cells and cell-nuclei 
was, however, gradually overthrown, and in 1855 Remak estab- 
lished the generalization that all cells are due to the division of 
pre-existing cells in such manner that the nucleolus first divides, 
then the nucleus, and lastly the cell-body. This schema could rest 
only on the facts of direct division and a superficial observation of 
indirect division. As soon as the latter was carefully studied by 
Hoffmeister, in 1867, he found that the nucleus disappears and 
two centres of attraction arise in the cell, in connection with 
which the daughter-nuclei were built up. These facts had been 
observed in animal-cells already in 1858, by Munk, so that the 
view that a cell must return to a cytode condition to divide and 
so, in a manner, be rejuvenated, and produce new nuclei endoge- 
nously, was fairly established. This school was strengthened by 
receiving the support of all who had observed the maturation of 
e ovum (except Warneck, 1850), for here it was seen that the 
rminal vesicle disappears before segmentation, and that the 
nuclei of the segmentation products arise as new structures, and, 
moreover, Valette St, George had, in 1866, shown that the ovum 
is a cell, the germinal vesicle a nucleus, and the germinal dot a 
nucleolus. 
complex nature of cell-structure was surmised by Brücke 
as early as 1861, although the microscope had then only re- 
vealed granules, and that these were at times arranged in a 
radiate manner with reference to the nuclei. 
In 1865, Frommann, through extended research, described the 
reticulate nature of protoplasm and generalized that this was the 
typical structure of protoplasm, but his views remained for many 
years unnoticed. 
2 = | Ia: eed the view that whenever a pro- 
