172 RUTH L. PHILLIPS 



Woodruff ('08) was led to believe that the death of Calkins' 

 animals might have been due to too constant a medium, and 

 accordingly began the cultivation of Paramecium in what he 

 termed a 'varied medium.' He believed that by collecting ma- 

 terial at random, he would provide infusions which would more 

 nearly approximate the natural environment of this animal 

 than a constant medium of hay infusion. The conclusion of the 

 procedure was truly remarkable, resulting as it did in the con- 

 tinuing of a single line for several years without a conjugation 

 and a very complete analysis of the life-history. 



Later, Woodruff and Baitsell ('11 a) were successful in culti- 

 vating Paramecium in a constant medium of beef extract. This 

 work established that mere constancy of medium, provided the 

 fluid used was suitable, did not interfere with the normal course 

 of the life-history of the animal. A constant medium did as 

 well as one which was continually varied. 



None of these investigators were working with a closely 

 controlled food. They were, therefore, continually dealing with 

 an important unknown factor. With a known food it is possible 

 to test further the effect of medium upon Paramecium. Two 

 types other than the 0.1 per cent standard timothy hay infusion 

 were used in this work. The infusion made with uncured swamp 

 hay differed from that made with cured timothy hay in that it 

 was prepared from a mixture of grasses which had grown in a 

 swampy lowland district, and was presumably different chemi- 

 cally from the standard infusion. The moneywort differed even 

 more. It was uncured when used, was extremely succulent to 

 start with, and much richer in cell sap than either type of grass. 

 The method used in preparing these infusions was the same, so 

 that gram for gram, equal concentrations were used. The result 

 showed that there was no significant difference in effect of the 

 two grass infusions. The moneywort tended to have a slight 

 stimulating effect for a short time, as shown in the case of A'B'C, 

 and in the fact that when used with such unfavorable foods as 

 J, K, and L, the duration of life of the animals was somewhat 

 greater than in the standard hay infusion. 



