ALGOLOGICAL NOTES 79 
nd I). 
nucleus is exceedingly oa median in ido And closely 
sresoad against the chloroplast, as in Epecien of Mougeotia. 
3.—Vegetative cells and cell- aivisisn of Mesotenium caldariorum. 
A-E, ‘piel vegetative cells. Cand D show the single chloroplast from the 
edge. E is eee nd view. ie ag in cell-division. py, pyrenoid. ol, oi 
globule. A-E, x 460. F-I, 
The cell-division of ace caldariorum is precisely as in 
the Placoderm Desmids. After the division of the nucleus a new 
cell-wall is laid down in an exactly transverse oe (fig. 3, F)ina 
manner very similar to that which occurs in the Zygnemacew. 
gradually disa appe ars from the per ghey in was and during its 
disappearance ene proba pa results from its conversion into 
mucilage), the part of the new wall belo onging to each semicell 
begins to bulge outwards, seatiitey a greater and greater con- 
vexity (vide fig. 3, H and I). This finally ict in a separation 
of the two daughter-co 
In May, 1918, large numbers of zygospores were formed in 
the cultures, more especially on the drier parts of the sandstone. 
Conjugation was quite normal as it occurs in the genus, and the 
zygospores were rounded-angular, with thick walls and several 
lamellose outer coats (fig. 4,C). The zygospores, after being in 
a state of partial desiccation for several months, germinated in 
September. Hundreds of germinating zy spoken: a were examined, 
and the outer lamellose coats gradually disappeared and the oily 
