STRUCTURE OF PROTOPLASM OF PARAMCECIUM. 9 



various Protozoa to chemical and electrical stimuli to see what 

 light these reactions might throw on the physical structure of 

 protoplasm. 



II. Reactions of the Protoplasm of Paramcecium and other 

 Protozoa to Chemical Changes. 



Paramcecia reared on cultures containing bread were used 

 chiefly in these experiments, although other protozoa were util- 

 ized for purposes of comparison. The method employed in the 

 experiments was as follows : The solutions whose action upon 

 the protoplasm was to be tested were made up in the proper 

 dilutions, and distributed among Minot watch glasses holding 

 about 10 c.c. of the solution. Pure, concentrated cultures of 

 the protozoa were obtained, and a drop or two added to each of 

 the dishes containing the solutions. At short intervals the 

 protozoa were examined to observe any structural changes in 

 the protoplasm. A 1/12 inch oil immersion was used to make 

 out the finer details. 



Great care is needed to distinguish between chemical and 



o 



osmotic effects. In order to obviate the possibility of modifying 

 the protoplasm through the extraction of water, all the solutions 

 were used in concentrations of a lower osmotic pressure than that 

 of the protoplasm, roughly equal to a #2/40 #2/50 cane sugar 

 solution. In some cases the dilutions were very great, and, inas- 

 much as distilled water or any solution of a lower osmotic pressure 

 will liquefy the protoplasm through the absorption of water osmot- 

 ically, there would be danger of confusing the osmotic and chem- 

 ical effects of the solutions, were it not for the fact that osmotic 

 and chemical liquefaction can be readily distinguished by the type 

 of protoplasmic structure produced by each means. 1 



All the chemicals used fall into two classes : 



i. Those that effect the protoplasm only through the osmotic 

 pressure of the solution. 



1 Miss Towle, in investigations now in progress at the University of Chicago, has 

 observed that paramoecia may live indefinitely in redistilled water. It is probable 

 that in this case, as in others mentioned in this paper, the variations in the structural 

 reactions are due to the differences in the chemical composition of the cultures in 

 which the paramoecia were reared. But this question of the structural effect of dis- 

 tilled water requires further investigation. 



