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SOME PECULIARITIES IN SPIROGYRA DUBIA. 
PAUL WEATHERWAX. 
A form of Spirogyra found on the campus of Indiana University early 
in the spring of 1918 has shown, in its natural habitat, as well as when 
subjected to new physiclogical Conditions, some phehnomenn of growth that 
are not only irregular for Spirogyra but also seem to be confined rather 
closely to the one species. 
The piant does not agree exactly with the description of any species 
given in the literature available, but it conforms fairly well with the «e- 
scription given by Wolle (1) and also the one given by Collins (2) for N. 
dubia Ke. This species, according to these descriptions, has two spirals, 
’ 
or “more rarely three”, and the fruiting cell is described as being slightly 
inflated. The plant observed here had regularly three chloroplasts, and 
the fruiting cells were not at all swollen. Wood (3) notes this same 
difference in the sporangial cell and suggests other variations but con- 
cludes that these characteristics are not sufficiently different to justify 
the description of a new species. A form showing a physiological peculi- 
arity similar to one shown by this plant, and probably from the same 
general location, is identified by Pickett (4) as NS. elongata (Berk.) Ke. 
When first found the plant formed a thin, green coating on a piece of 
rusty sheet iron lying in runbing water. Most of the filaments were only 
one to three cells in length and were probably developing from zygotes, 
but the striking thing noted was the highly differentinted basal cells (Tig. 
3) by which the filaments were attached to the mud on the iron, and, 
in maby cases apparently to the rough surface of the iron itself. 
Sonditions were favorable for rapid growth, and ten days later the 
filaments were three or four inches in length and composed of many cells, 
but still as firmly attached as would have been filaments of Cladophora 
of the same size. The root-like basal cells had grown very much longer 
znd had assumed a variety of peculiar shapes. Their walls had thickened, 
and their coutents were just beginning to show signs of decomposition 
(Bie: 5): 
