608 Wolfe. — Cytological Studies on Nemalion. 
attention. The minuteness of the cell and cell structures, together with 
the complexities attendant upon the act of fertilization, may be in a measure 
responsible for this. Perhaps also the group has been less attractive owing 
to the fact that it appears to be modern, highly specialized and terminal, 
hence not in itself a factor in the evolution of the plant series. Neverthe- 
less, it has seemed to the writer that it would be interesting to know how 
far the nuclear phenomena in this side line parallel those in the direct line 
of evolution 
With a view to filling this gap in our knowledge a large supply of 
Nemalion multifidum , A g., was collected at Woods Holl, Massachusetts, at 
different times during the summer of 1901. The structure of the frond and 
the simple sexual relations make this a favourable type for such a study. 
Consisting of a central axis of intertwining filaments from which branches 
radiate perpendicularly, and, in addition, having apical growth, a longi- 
tudinal section presents vegetative cells in division at the growing point, 
and all stages from the youngest procarp backward to the mature cystocarp. 
Other demands upon the writer’s time have delayed the completion of this 
work. It was begun in the Botanical Laboratories of the University 
of Chicago and continued at the Marine Biological Laboratory at Woods 
Holl, under the direction of Dr. B. M. Davis, and brought to completion 
under the supervision of Professor Roland Thaxter at Harvard University. 
The writer wishes here to express his thanks both to Professor Thaxter and 
to Dr. Davis for constant suggestion and criticism. 
Aside from phenomena related to chromosome-reduction, which was 
the primary purpose of this investigation, during its progress a consider- 
able body of information has been gathered bearing on other matters 
of cytological interest. For convenience these results will be discussed 
under the following heads : — 
A. Methods. 
B. The Cell. 
(a) Structure of the Chromatophore. 
(b) Division of the Chromatophore . 
C. Maturation and Sexual Reproduction. 
[a) Oogenesis. 
(b) Spermatogenesis. 
{c) Fertilization and Development of the Cystocarp. 
D. Mitosis ( centrosome , spindle , &c.). 
(a) The Nucleolus. 
(b) Reduction. 
