On the Retention of Vitality by Alga. 103 
variable number may lie more or less parallel within a structureless 
gelatinous sheath which later becomes diffluent and very difficult 
to see. Probably owing to unequal growth, the parallel strands of 
Fio. 2. " A nab an a oscillarioides Bory var. tnrtsiris nov. var. A forma 
minor, B forma major, h. heterocyst, s.h. seriate heterocysts, s. spore, v. 
vegetative cell. 
