Reproduction of Cyst opus Candidus , Ldv. 323 
in minute drops at this stage, and that it will not dissolve 
even after a long soaking in alcohol, ether, and chloroform. 
It is of the same nature as the dense protoplasmic mass 
which appears in the fertilizing tube at the moment when it 
begins to grow, and is produced probably by an accumulation 
of stainable granules from the protoplasm. This dense mass 
of protoplasm can be observed in oogonia of all stages, such 
as are figured in Figs. 8 to 22 . Shortly after its appearance, 
one of the nuclei produced by the division in the oogonium 
comes into close contact with it and gradually becomes more 
or less completely embedded in it. All the other nuclei pass 
to the periplasm, leaving this single nucleus in the centre 
as the nucleus of the ovum (Figs. 13 and 14). We may 
consider that at this stage the oosphere has become differ- 
entiated, although its cell-wall has not yet appeared. It is 
interesting to note that the wall of the oosphere does not 
form until just at the time when fertilization takes place, or 
shortly afterwards. 
The Division of the Nucleus. 
As already pointed out, the division of the nucleus in the 
oogonium is karyokinetic and is very similar to the normal 
process as described in the higher plants. The more the 
structure of the nucleus is investigated in the lower plants 
the more clearly does the fact become apparent that, instead 
of a much simpler and more rudimentary type of nucleus 
than that so well known in the higher plants, it appears to 
be almost exactly similar, the former differing from the latter 
in no essential respect, except perhaps as regards the presence 
of centrospheres. Indeed it appears to me that in some 
cases, certain details of structure come out more clearly in 
these lower plants than in the higher, provided a sufficiently 
good magnifying power be used. In any case I think we 
may fairly arrive at the generalization that simplicity of 
vegetative structure does not necessarily mean simplicity 
of cytological structure, and that it is probable that further 
