PH ZOPHYCEA 103 
interstitial cells of the thallus which divide 
up ail San and ‘longitudinally to form pluri- 
locular spofangia. These occur generally in numbers 
adjacent to éach other. The other kind, which 
appear to be more common, arise by a process from 
a superficial cell (or one of the cells where the 
thallus consists of a single row). This process divides 
Fic. 25.— Kjellmania sori- 
Jera, Filament with young Fic. 26. — Stictyosiphon Decaisneii. 
sorus sporangia. Highly mag- Transverse section of thallus showing 
nified. (After Reinke ) sporangia, Highly magnified. 
‘up by walls running transversely to the axis of 
the plant into a sorus of cells, each of which ac- 
quires an arched apex and divides farther into 2-4 
loculi one above the other. Each loculus produces 
a single zoospore. The whole sorus is thus in this 
case the product of a single superficial cell. The 
occurrence here and in Giraudia of two kinds of 
