194 ■ W. A. Matheny 



The single-celled animals are especially well adapted for the 

 investigation of physiological activity. The ease with which they 

 lend themselves to experimental methods and the simplicity of 

 their structure make it possible to arrive at an accurate analysis of 

 the effects of the stimulus in question. 



This problem was suggested by Prof. .C. F. Hodge under whose 

 direction a series of similar experiments are now being carried on. 



METHODS 



Hay infusion was used at first as a culture-medium, but later it 

 was found that alfalfa, on account of its uniformity, gave much 

 better and more reliable results. A comparison of these culture- 

 media is given in Table i. 



The infusion was made as follows: Fifteen grams of hay or alfalfa 

 were boiled for one minute in 1500 cc. of tap water. This was 

 prepared each day late in the afternoon and was used the next 

 morning. 



A "wild" Paramecium was taken from a hay mfusion in labora- 

 tory and placed in a watch glass in 8 cc. of fresh solution. At the 

 end of twenty-four hours the hay solution was renewed. On the 

 second day there were paramecia enough present to start the experi- 

 ment. 



At first, six cultures, each comprising four lines, were carried. 

 Afterwards others were added. Using a pipet drawn out to a fine 

 point, four individuals were transferred to four depression slides, 

 each having a capacity of about five drops. Pure infusion was 

 added and this started the control culture. In a similar manner 

 cultures were started in the following percentages of alcohol, i 

 per cent, yV per cent, ^g per cent, iV per cent, yio per cent. 

 A few days later cultures were started in 2 percent, 3 per cent, 

 4 per cent, 5 per cent, and 6 per cent solutions. 



In order to determine the resistance of paramecia to alcohol 

 in greater quantities, the following experiment was performed. An 

 individual was taken from the control and isolated in pure infu- 

 sion. When it had made three divisions, a culture of four lines 

 was started in pure solution for control. Another culture of four 



