LIFE-HISTORY OF BOTRYDIUM. 373 
Lrre-History or Borryprum. 
Ueber ee ey granulatum. Von I. Rosrarmnsxr und M. Woronry. 
t. Zeitung, October, 1877. With 5 plates.) 
THE sin Sih little plant with which this memoir deals has hitherto 
been more remarkable for the number of names it has borne than for 
the knowledge snes ‘of its history. ‘anes every author who has 
had to deal with it has qu ietly passed on, pi te himself with the 
addition of another synonym ; but as “ever et has its billet,” so 
has every alga an actual or potential pret sia of its life-processes. 
These, in the case of Botrydium granulatum, are now before us very 
nearly in their entirety, and we propose briefly to ran over them 
If a green ie ‘‘ordinary zoosporangium ”—be place ced in 
a drop ‘pe mbers of zoospores are formed from it either 
towards the se om of the day or during the night. If, however, 
t 
dro 
its mcrae collaas in the unde pitti branches, which ay fill in 
e form of a necklace of cells. These cells are ae ee of three-fold 
development firstly, if placed in a drop of w ane membrane 
wells up, breaks through the wall of the root Nery koi $s an under- 
si zoosporangium ; secondly, a row of these coat elle laid on 
- moist earth grow up directly into Sooskeee plants ; lastly, if the cells 
be left to themselves, care being ta ken to keep the culture moist, they 
: e a bladder, and send out a hyaline root-pro- 
longation, the wall of which is very much thickened under the small, 
an organ which, if dried, retains its capacity for germination through- 
out the entire year, and shows no o day-and-night relation in the forma- 
tion of its zoospores, & fact in which it resembles the underground 
zoosporangiu The vegetative plant can multiply either by the con- 
striction and ultimate separation of portions of the cylinder, or by 
direct production of zoospores, or by becoming an ordinary Zo oospo- 
rangium, or even & gium. When, “however, itis ex 
to drought or sunlight the chlorophyll, breaks up into cells in number 
proportional to the i the mother-plant; the green contents of 
these cells or ‘‘ spores’ change a time. in 
the spores become zoosporangi h a swarm of biciliated Z00- 
rom whic 
sporesescapes ; these die when isolated, butunder ordinary circumstances 
they copulate — two or sever ther. The round isospore 
resulting his copulation developes into an 07 ordinary vegetative 
plant, a "ortnight being necessary for completion of its gokart but 
