252 R. W. HEGXER. 



dishes in the laboratory for about eight months. These bladders 

 were almost entirely free from euglenas although when first 

 brought into the laboratory the bladders were infected with 

 large numbers. This may be accounted for as follows. Bladders 

 do not live very long, but gradually loose their chlorophyll, 

 break away from the plant and drop to the bottom. Here they 

 disintegrate in course of time thus liberating any euglenas con- 

 tained in them. These euglenas either live in the water or are 

 captured by the new bladders that are continually developing. 

 Their habitat within the bladders is very restricted and their 

 escape from the old bladders and reinfection of new bladders 

 difficult. Probably for these reasons, the number of euglenas 

 decreased in plants that were kept under laboratory conditions. 

 Free-living euglenas are captured by bladders and live normally 

 and multiply within bladders. Bladders were immersed in cultures 

 containing many free-living euglenas or euglenas were injected 

 into them with a fine pipette. 



Experiment 2. One of ten detached bladders became infected in 24 hours with 

 one active free-living euglena. 



Experiment 4. Thirteen attached bladders failed to become infected in 48 

 hours. 



Experiment 23. Eleven of twenty detached bladders became infected in 40 

 hours. The numbers present in these bladders were as follows: 3 bladders with 

 one each; 3 with 2 each; one with 3; and 4 with 6 each. The average number 

 per bladder was 3.3. These bladders were examined at intervals of 3 days for 

 9 days. They all remained infected during this period. At the end of 3 days the 

 number had increased in 6 of the bladders; the average per bladder increased 

 from 3.3 to 6.7. A further increase took place during the next three days, the 

 average rising from 6.7 to 15.1. During the succeeding three days this average 

 increased from 15.1 to 20.1 per bladder. The numbers present in the individual 

 bladders at this time were 50, 40, 30, 30, 16, 10, 8, 7, 6 and 4. One infected bladder 

 had broken down and allowed the euglenas to escape. 



Experiment 20. Euglenas were injected with a fine pipette into 10 bladders 

 attached to 4 stems, each bladder receiving from one to eight specimens. These 

 were examined on 7 days during the succeeding period of 9 days. The number 

 increased in 7 of the ten bladders; the other 3 bladders became detached before the 

 observations were completed. 



These experiments show that bladders may become infected 

 with free-living euglenas and that these not only are not destroyed 

 within the bladders but appear to move about normally and 

 reproduce. Normal activity and reproduction also occur in 

 attached bladders into which euglenas have been injected. These 



