Sapa en oe 
1901 | PHYSIOLOGY OF POLYMORPHISM IN ALGAE 293 
substance had to be chosen in which the plant would live and 
grow for some length of time. Also it was necessary that the 
culture media be of such nature as not to be readily attacked by 
bacteria and fungi. After several failures, the two saccharoses, 
lactose and cane sugar, were hit upon for this purpose. The 
former is far the better, but the latter serves very well. Cultures 
in these may be continued for two, three, or even four weeks 
without undergoing fermentation sufficient to affect the alga 
appreciably. 
Tables I and II give the results of some representative cul- 
tures in these solutions. At the left are those in lactose, at the 
right those in cane sugar. In the first table the original mate- 
rial was of the palmella form; in the second, of the filamentous. 
The concentrations are given in terms of a normal solution (z= 1 
gram molecule per liter), and are placed in the columns headed 
“concentration.” In the columns headed ‘first response,”’ 
Sp. F. denotes that zoospores were produced in great numbers, 
and germinated as usual to form filaments. A single asterisk 
(Sp.*) shows that the spores did not germinate. Filaments 
produced from the original masses are denoted by F in this col- 
umn. Two asterisks (Sp.**) show that few zoospores were pro- 
duced, and that these failed to germinate.. P denotes the 
palmelloid form; P> the rounding up of cells as if going over 
into palmella. In the columns following those indicating the 
response is given the time of response in days; 2-12 denotes 
that the response was observed two days after the making of 
the culture, and continued for ten days. The second response 
is the result of evaporation, and comes after a somewhat longer 
time than the first. The time for it is given in days after the 
making of the culture. 
In general, solutions of low osmotic pressure produce zoo- 
Spores and filaments, while those of high pressure produce only 
the round-celled form. This is in accord with the results 
obtained with solutions of mineral salts. However there is one 
difference in the behavior of the palmella form in solutions of 
electrolytes and non-electrolytes. This is brought out by Table 
