336 BOTANICAL GAZETTE [NOVEMBER 
stationary, the other executes in succession several jerks or nods as if 
striking at something; then it enters upon another series of evolutions. 
After a short time thus engaged, the activity of the zoospore increases, 
the field covered by its evolutions becomes larger, and it is lost 
from the field of the microscope. In some cases which were timed 
the zoospores were separate in 25~30 minutes from the time the ~ 
Fic. 6.—Lagenidium americanum Atk. in zygosp f Spirog) A, Bsome empty 
and some mature prosporangia; C from one prosporangium the protoplasm has just 
issued from the exit tube; D plasma sphere or zoosporangium proper free from the 
exit tube and floating in water; E formation of cilia where a zoosporangium is swim- 
ming around as a multiciliat ; F, G different stages in formation and separation 
of zoospores, the groups swimming around like a pandorina colony; H mature and 
separate zoospore. 
protoplasm passed from the exit tube. In those cases where the - 
plasma vesicle at the end of the tube becomes free and floats away, — 
the cilia develop on its surface, and it at first presents the appearance 
of a multiciliate spore. Later the divisions occur in such a way aS 
to leave two cilia with each forming zoospore, and the colony then 
resembles a pandorina colony. 
Lagenidium americanum, n. sp.—Plant body in the form of irregular tubes, 
much branched, curved, and of unequal diameter, confined within the host zygote, 
3-8 4 in diameter. Exit tubes slender, short, 2 4 in diameter, varying in len 
but extending a short distance outside of the gametangium wall, of equal diameter 
from the point where they pierce the wall of the zygote to the outer free end, thus 
differing from the exit tubes of L. entophytum (Pringsh.) Zopf. Exit tubes arising 
from the end of hyphae or branches, or from the convex side of curved or enlarged 
portions. Zoosporangia of varying size, irregular and often branched, formed 
from segments of the thallus. Plasma sphere at the end of the exit tube often 
becoming free and floating away (the cilia then forming on the outside of the 
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