BRIEPER ARTICLES, 
NOTES ON THE PHYSIOLOGY OF STIGEOCLONIUM. 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY. LxXX. 
(WITH THREE FIGURES) 
THE experiments with which this paper has to deal fall into two groups, 
those with low temperatures and those with sea water. The subject for 
experimentation was the polymorphic form of Stigeoclonium with which 
I have been concerned in several preceding papers.*. As has been already 
shown, this alga takes either of two very distinct forms according to the 
nature of the medium in which it is grown. In solutions of relatively high 
Osmotic pressure and in those of low pressure to which stimulating metallic 
salts have been added, the palmella form is assumed. This consists of 
nearly spherical cells lying singly or in irregular groups. In unpoisoned 
solutions of low osmotic pressure the alga grows as branching filaments 
composed of cylindrical cells. When such filaments are placed in a poisoned 
solution or in one of high pressure, they become transformed to the other 
form by the simple rounding off of their individual cells. In general the 
Production of zoospores is checked where the palmella form is produced, 
ut there are a number of exceptions to this among the metallic poisons.? 
In such cases this process may be accelerated even where the germination 
and growth of the zoospores are inhibited. 
I. Low tem peratures.—Since high pressure of the medium acts to pre- 
vent water absorption, and since low temperatures are known to cause the 
extrusion of water by both plant and animal cells,3 it occurred to me that 
__? Livinesron, B. E., (1) On the nature of the stimulus which causes the change 
n form of polymorphic green algae. Bor. GAZETTE 30:289-317- 1900. 
~_—+ (2) Further notes on the physiology of polymorphism in green algae. 
Bor. Gazerre 32:292—302. 1901. 
~~» (3) The réle of diffusion and osmotic pressure in plants. Chicago. 1903 
Part II, Chapter III. This chapter was reprinted as “The effect of the osmotic pres 
“ure of the medium upon the growth and reproduction of organisms. Chicago. 1993. 
>» (4) Chemical stimulation of a green alga, Bull. Torr. Bot. Club 32:1-34. 
figs. bi 1905. 
? Loc. cit. (4). 
5 Loe. cit. (3), pp: 75 and 141, and the references there given. 
