The Life History of TtUina Magna 385 



culture, brought forward in 1904. From his observations on the 

 appearance of Stentor in the culture medium, Peters concluded 

 that, as there is a constant change taking place in the growth of 

 a culture caused by fermentation, there is also a corresponding 

 change in the life of the culture. Paramecium, Euglena and others 

 appear at an early period when the fermentation is active. Stentor, 

 on the other hand, does not appear until the extreme acidity has 

 decreased, at which time the earlier forms begin to die out. There 

 must be some other reason, however, to explain the nonappearance 

 of Tillina in the new culture jars, which were examined very fre- 

 quently. Possibly the organism is an intestinal parasite of the 

 horse, which may also lead a free living existence for a short time. 

 Its non-appearance in the fresh jars might be explained in this 

 case if the culture material was not infected. 



II MATERIAL AND METHODS 



Since Tillina stock was found in a jar containing a culture of 

 horse manure, in order to have the artificial medium as near like 

 the normal as possible, a solution was made often grams of man- 

 ure in 60 cc. of water. This was brought to a boil, filtered and 

 allowed to stand. In general it was found better to use the me- 

 dium that was 24 hours old. Fresh medium was made every 

 two or three days and the cultures were examined every day. 

 Attempt was made to find another medium. A hay infusion was 

 prepared according to the method of Calkins ('02). Then the 

 animals were brought gradually into the new medium, starting 

 with a solution of I hay infusion, and f medium, and increas- 

 ing the amount of hay each day. In no case could the animals 

 live in pure hay infusion, death occurring almost immediately. 

 I was able to carry a culture for about a month in a solution of 

 ^ hay and ^ medium, but they were not as healthy as those in the 

 straight medium. An oat infusion was tried, with no better suc- 

 cess, and the so-called "normal" medium was finally decided 

 upon as best for the experiments. 



The methods used in these experiments are the same as those 

 of Calkins ('02) and Woodruff ('05). In brief, a small chamber 



