STUDIES ON EUGLENAMORPHA HEGNERI. 157 



roots were still more plainly visible, but the external portions did 

 not show. The small individual with three flagella and a body 

 profile intermediate between the two varieties (Fig. 26) might well 

 be the product of such a division. In pellucida new flagella are 

 probably developed soon after division, since so many of them have 

 the even numbers, four or six. Fig. 36 might represent the prod- 

 uct of either mitotic or amitotic division, and its small size and two 

 flagella indicate that it is a daughter of a four-flagellated parent. 

 A summary of the comparison between these two varieties is 

 given in Table I. 



C. Transition Stages. 



Although the two varieties just described are so strikingly dif- 

 ferent in their typical forms, enough transition stages between 

 them have been found to make it almost certain that the green or 

 type variety transforms into the colorless or pellucid one. This 

 transformation probably takes place in more than one way. As 

 described above, the mitotic division of the green variety within 

 the host seems to be accompanied by the loss of the chromatic 

 swellings on the roots of the flagella (Figs. 22 to 25). The pres- 

 ence or absence of these swellings has proved to be the best cri- 

 terion in fixed and stained individuals for distinguishing between 

 the two varieties. Hence it seems probable that division of the 

 green variety is accompanied by transformation. 



Transformation probably takes place directly without division. 

 Stages showing the gradual loss of chlorophyll accompanied by 

 the gradual swelling of the nucleus to the expanded condition char- 

 acteristic of pellucida are not hard to find (Figs. 9 to n, 17 and 

 20). While this series of changes may lead to complete degenera- 

 tion as observed on some slides, in other cases the}' may lead to 

 the colorless variety. The chromatic swellings may disappear be- 

 fore the chlorophyll has all broken down (Figs. 18, 19, 21) or 

 before the change in the direction of the surface striae (Fig. 18). 

 In Fig. 1 8, however, it is seen that one of the three flagellar roots 

 still retains a remnant of its chromatic swelling. Fig. 19 might be 

 a further stage in the transformation with the swellings entirely 

 gone, the striae changing their direction, but chlorophyll still pres- 

 ent. The individual shown in Fig. 20 has the swellings and sur- 

 face striae of the green variety, but the chloroplasts have largely 



