258 SEAWEEDS 
CHROOCOCCACER. 
General Characters—The Chroococcacee are dis- 
tinguished from the Nostocacee not only by their 
unicellular character, but more particularly by the 
fact that they do not produce hormogonia, but uni- 
cellular reproductive cells. Typically cell-division 
does not occur in one direction only leading to the 
formation of trichomes, but the direction varies with 
more or less regularity, and since the daughter-cells 
remain together in colonies within the original 
envelope for a number of generations (Glawocapsa) 
irregular gelatinous masses. are thus formed. The 
order is divided into two families, Chroococcew 
and Chamcsiphonee, which may for convenience be 
treated separately. 
The Chroococcew are best known by the genus 
Gleocapsa. After each division of the mother-cell 
the daughter-cells may be free to develop indepen- 
dently, but usually they are held together by the 
common gelatinous envelope for a succession of 
generations. Spores are formed after the simul- 
taneous change in habit of the whole colony of cells, 
and in place of the gelatinous membrane a thick 
membrane, rough on the outside, is developed. The 
spore repeatedly divides, and soon forms in this way 
a new normal colony of vegetative cells. 
The Chamesiphonee possess in Hyclla a genus of 
perforating Alge, which at first sight appears to be 
an approach to the Wostocacee, since the cells occur in 
filaments. They are, however, so many individual 
