1906] YAMANOUCHI—POLYSIPHONIA VIOLACEA 4ly 
together by broad protoplasmic strands. These protoplasmic com- 
munications make possible the movement of the nuclei in the auxiliary 
cells towards the pericentral cell. This general cell union finally 
results in the formation of a large irregular cell, the central cell, 
as it was called by previous investigators (PHILLIPS 60, and others), 
containing a number of nuclei. Two of these nuclei, as previously 
Stated, are sporophytic and derived from the mitosis of the fusion 
nucleus in the fertilized carpogonium; the other nuclei, perhaps 
three or four in number, are gametophytic and derived from the aux- 
iliary cells. The two sporophytic nuclei lie in the upper part of the 
central cell and the gametophytic nuclei below. There are not as 
many gametophytic nuclei in the large. fusion cell as might be 
expected, because some of them have already broken down and the 
others generally show signs of disorganization. 
The two nuclei of sporophytic origin give rise to a series of mitoses 
(ig. 127), and the central cell now develops several lobes, into each 
of which a single sporophytic nucleus generally passes (fig. 128). 
The nucleus contained within each lobe divides once more (jigs. 
729, 130) and a carpospore is. cut off terminally (fig. 132) from the 
lobe by a cleavage furrow, the lower portion remaining as a stalk. 
cell by which the carpospore is attached to the central cell (fig. 132). 
The chromosomes appearing in the mitoses previous to the forma- 
tion of the carpospore are clearly 40. in number. There is therefore 
ho chromosome reduction at. this period in the life history of Poly- 
siphonia, for the sporophytic number 4o enters the carpospore and, 
48 previously described, appears with the first mitosis at its germina- 
"ton. The period of chromosome reduction in Polysiphonia is at 
the time of tetraspore formation, as will. be discussed presently. 
This is an important matter in relation to WoLFE’s (86) account of 
Nemalion, where he reports chromosome reduction as taking place 
Just before the formation of the carpospores. 
After the formation of the carpospores. the central cell increases 
ereatly in Size, absorbing the stalk cells (fig. 133); and finally the 
cell of the axial siphon becomes involved in these extensive cell unions, 
Which are probably concerned with the nourishment of the carpo- 
“Pores, since sixty or more,as a rule,are developed in a single cystocarp. 
ile the Carpospores are being formed, the characteristic envelop 
