310 BOTANICAL GAZETTE [ NOVEMBER 
more probably belongs to some developmental stage of a 
desmid, possibly a zygospore, than represents the vegetative 
condition of any unicellular alga. More recently De Toni (3) 
describes the genus as an exceedingly doubtful one, suggesting 
that the large cells resemble fern prothallia, and that we may 
expect to find it related to the higher cryptogams. Wille (7), 
in Engler and Prantl, places Eremosphaera among the Pleuro- 
coccaceae. The last investigator to have had this alga under 
consideration is Chodat (1), who believes that its affinities are 
such as to put it with the Volvocaceae ; furthermore, the results 
of his observation show a condition of polymorphism which 
has not hitherto been suggested. In addition to the regular 
vegetative condition and the ordinary methods of multiplication, 
which will be described later, Chodat found a number of transi- 
tion stages which he variously designated as ‘ Gloeocystis” 
forms, ‘‘Palmella” forms, ‘‘Schizochlamys” forms, ‘ Centro- 
sphaera” forms, etc. According to Chodat, these various 
stages of Eremosphaera are actually the same thing as the 
genera which they resemble, and we can no longer recognize 
them as distinct species, but must include them all under the 
single name Evemosphaera viridis. It was with the desire to clear 
up the question as to the polymorphism of this form, and to 
settlé, if possible, its life history and affinities, that the investi- 
gation concerning this alga was undertaken. 
MATERIAL. 
The specimens first studied were secured from a small pool 
formed by a sluggish brook running through a marsh near Ridge 
hill, Mass. Although the pool is quite small, there is usually 
plenty of water, and at no time during the year is the material 
absent from this locality. There was no sphagnum growing in 
the pool, as seems usually to be the case where Eremosphaera is 
found, but an abundance of Zygnema, Spirogyra, and other Con- 
jugatae, notably Micrasterias, was frequently present. The 
plants were first discovered in May 1897, when they numbered 
about twenty to the cubic centimeter. Since that time they 
