300 BOTANICAL GAZETTE [NOVEMBER 
In all, 278 cultures were made and record kept of each for 
five to fifty days. They were made at all seasons of the year 
_and in two different years separated by a period of nine months, 
during which the material was kept alive and changes made from 
time to time but no records kept. It will be seen that there are 
two possibly very different questions to be answered in the prob- 
lem before us. First, what are the conditions that bring abouta - 4 
change from'the palmella form to the filamentous form; second, 
what are the conditions that bring about the reverse change? bs 
shall divide the experimental data which are to follow into two 
groups corresponding to these two questions. Details of typical 
responses are given in the explanation of plates. 
A. RESPONSES OF THE PALMELLA FORM, 
In table III are given the results of fifty-five transfers of 
palmelloid cells into the different solutions. For convenience, 
all cultures having the same osmotic pressure are brougiit 
together. In the left hand column the letters denote the chem 
ical content of the fluid, as just described. The number of eae 
tures made is given in the second column. In the third 18 
recorded the number of cultures in which the cells multiplied 
but remained of the palmella form after twenty to twenty-five ‘ 
days. Columns four and five (Filaments) give the eee” a 
which filamentous branches were produced from the orig! : 
masses in five to twenty-five days. Those in column four 2 
duced few filaments, but continued mostly as palmella ; pee o 
column five produced many filaments. In columns six and ghee 
(Zoospores) are the numbers which produced few or Fe 
Spores within fifteen to twenty days. Column eight oo” ts 
those which produced no zoospores for twenty-five ye pee 
The last two columns record cultures on which definite ner | 
tians are lacking, the first with regard to the proces ee at 
spores, the second with regard to the production of flea 
the edges. | 
