228 BOTANICAL GAZETTE ° [MARCH 
seems to be with certainty fourteen, and that of the sexual plant is about seven. 
Spindle fibers are formed, apparently by the rearrangement of the linin thread, 
so that the spindle is intranuclear. Kinoplasmic caps are present only during 
the nuclear division. The changes in the nucleus of the tetraspore mother cells 
are striking. The nucleolus fragments into several rounded bodies of various 
sizes, which after continuous fragmentation yield 12-14 rounded masses of chro- 
matin of about the same size. These bodies become again irregular in form, and 
fuse with one another, so that their number is reduced by more than half. This 
stage LEwIs considers to represent synapsis, but it differs from the usual type. 
Fourteen chromosomes then appear and are scattered in the nuclear cavity. 
After telophase of the first division in the tetraspore mother cell, the daughter 
nuclei rest before commencing the second division. In the sporelings from 
tetraspores about six or seven chromosomes appear; in those from carpospores 
the number has not been ascertained exactly, but the author believes them to be 
diploid. Cell division in sporelings occurs usually when about sixteen nuclei 
are present, so that the coenocytic condition is attained very early in Griffithsia. 
Tetraspore-like structures on an antheridial plant have been found in only one 
case out of all plants examined. In this structure the cleavage furrow either does 
not reach the center of the cell or no trace of it occurs. Nuclear conditions have 
not yet been followed thoroughly. ‘ 
From the cytological evidence brought forth in this paper, LEWIS considers 
that there exists in Grifithsia Bornetiana an alternation of generations similar 
to that described for Polysiphonia violacea by the reviewer. The fusion nucleus, 
which contains fourteen chromosomes, produces the cystocarp in which are formed 
carpospores. The nuclei of tetrasporic plants contain fourteen chromosomes, 
carpospores. In tetraspore formation the number is reduced one-half, 
seven chromosomes and which bears sexual organs. 
As to whether the alternation of generations in Griffithsia is to be regar ded as 
antithetic or homologous, the conclusions are as follows: (r) ‘There is in Griffith- 
sia an antithetic alternation of generations, the gametophyte being represented 
by the sexual plants, the sporophyte by the sporogenous cells of the cystocatP: 
(2) “In addition to this there is a regular succession of tetrasporic individuals and © 
sexual individuals. The tetrasporic individuals resemble the sporophy 
number of chromosomes; they resemble the gametophyte in morphological 
differentiation. They are to be considered as a phase of an homologous alter 
nation of generations, not the equivalent, wholly or in part, of the sporophytes “ 
archegoniates.” To draw these conclusions, Lewis has put more weight upon 
_ the two following factors than upon the fundamental chromosome diff rent 
between sporophytic and gametophytic nuclei: (1) the outer morphological 
similarity of the tetrasporic plant to the sexual plant; (2) the fact that either seems 
capable of producing the outer morphological equivalent of the reproductive 
