STUDIES ON EUGLENAMORPHA HEGNERr. 165 



its adaptation and has not yet established itself as a regular in- 

 habitant with its own protected stages for reaching a new host. 

 The final steps necessary to establish it as a new species of parasite 

 seem not to be very great, but of this one can not be certain. This 

 is an alluring picture of evolution in progress, yet the information 

 at hand is scarcely sufficient to assert positively that the picture 

 is real. 



SUMMARY. 



1. Euglenamorpha hegneri is the name proposed for a new 

 Eugletia-Yike flagellate found in the rectum of tadpoles and first 

 reported by Hegner ('22). 



2. Most of the tadpoles examined were those of the bullfrog 

 obtained from the pond in the Botanical Gardens of the University 

 of Pennsylvania. Some tadpoles of Rana palustris collected by 

 Dr. C. L. Parmenter and fed on vegetation from the same -pond 

 were also examined. About 60 per cent, of the 117 bullfrog tad- 

 poles examined in 1922 and 16 per cent, of the 30 examined in 

 1923 harbored Euglenamorpha. About 60 per cent, of the 9 tad- 

 poles of Rana palustris examined in 1922 and also of the 35 exam- 

 ined in 1923 were infested with this flagellate. Eight tadpoles of 

 R. clamitans(?) and 8 of Hyla vcrsicolorC?) examined at Woods 

 Hole in August, 1923, all contained Euglenamorpha. 



3. There are two varieties : one, green, is the type, and the other, 

 pclluclda, is a colorless derivative. Typical individuals of the two 

 varieties are so different that without intermediate stages they 

 would be put into different species or into different genera. 



4. The green (type) variety has a cylindrical or cigar-shaped 

 body, chlorophyll, stigma, paramylon granules, compact nucleus, 

 three flagella with swellings on their roots near the stigma, surface 

 striae passing from the left over to the right. It may occasionally 

 divide bv mitosis within the host. 



*/ 



5. Variety pcllucida has an elongately conical body, little or no 

 chlorophyll, no stigma, no swellings on the usually four or six 

 flagella ; has enlarged reservoir, nucleus expanded, and surface 

 stria? usually passing from right over to the left or longitudinal. 

 Amitosis as well as mitosis occurs frequently in the host. 



6. Transitions between the two varieties are found and it is 

 believed that the green variety transforms into the colorless one. 



