FRESH-WATER ALG. 243 
mention of it in the writings of the alchemists, by 
whom it was highly esteemed on account of the mys- 
terious virtues which it was supposed to possess. 
The structure of this plant, simple as it appears, 
is very curious and interesting. Examined under 
the microscope, it is found to consist of a number 
of slender moniliform threads or necklaces of 
spores, invested with a firm and copious gelatine, 
which originated at an early stage from each in- 
dividual thread, but has now become the common 
envelope of the whole mass. The plant is propa- 
gated by the division of these threads into their 
individual joints, which burst through the common 
jelly, and become dispersed in the water, where 
they are endowed with spontaneous motion, en- 
abling them to contend against currents. These 
fragmentary threads divide longitudinally, at last 
constituting a bundle of new threads, which gradu- 
ally, by increase of the gelatinous elements, assume 
the normal form of the species. Larger globular 
cells called sporanges, each producing one resting- 
spore which breaks out from it in germination, oc- 
cur at intervals in the filaments, with others devoid 
of endochrome. 
Another allied species is the mountain dulse of 
the Scotch (Palmella montana), occurring very 
frequently in patches of a deep but dull purple 
colour, in moist, stony places, on the mountains of 
