172 ROBERT W. HEGNER. 



euglenoid. One tadpole that was examined the following day 

 contained many living euglenoids most of which were rounded 

 and quiescent but a few of which were extended though sluggish. 

 Besides these euglenoids there were large numbers of euglenoid 

 chromatophores present proving that many specimens had been 

 broken down within the digestive tract. The feces of the re- 

 maining four experimentally fed tadpoles were found to contain 

 living euglenoids and these in the course of the next two weeks 

 must have passed through the digestive tract of these tadpoles 

 and been reingested again and again. One tadpole was killed 

 and examined four days after feeding, another 13 days after 

 feeding and the last two 20 days after feeding. The first two of 

 these contained living euglenoids in both intestine and rectum, 

 but the other two, which were prevented from reingesting their 

 feces for a period of 7 days were entirely free from euglenoids. 

 These results show that the free-living euglenoids used in this 

 experiment had a higher degree of resistance to digestion within 

 the tadpole than those employed in the first experiment but were 

 unable to maintain themselves for a period of 20 days within the 

 digestive tract. 



A third experiment of a similar type was carried out with 

 euglenoids obtained from the bladders of the bladderwort, Utricn- 

 laria. I am indebted to my colleague, Mr. Bruce D. Reynolds, 

 for calling my attention to this form and obtaining material for 

 me. Plants obtained from a pond on the campus of the Johns 

 Hopkins University were well supplied with these euglenoids 

 although the surrounding water was entirely free from them. 

 The numbers of euglenoids counted in ten bladders ranged from 

 8 to 510 in each, with an average of 215. Euglenoids were dis- 

 sected out of 90 bladders and placed in a dish of water with three 

 tadpoles of the green frog. The total number of euglenoids in 

 this dish was thus about 20,000. All of these had disappeared 

 from the water by the following day and none could be found in 

 the fecal material in the dish. One tadpole was examined after 

 two days and the other two after three days. No euglenoids 

 were found in any of them. This type of euglenoid, therefore, 

 is unable to withstand the digestive juices of the tadpole, although 

 resistant to the secretions within the bladder of the Utricularia 

 plant. 



