382 F. W. GA]\[BLE AND FREDERICK KEECLE. 



translocation of their stored reserves as by dig-estion of tlie 

 entire algal cell. From this summary it will be clear that 

 the prevalent opinion as to the algal nature of other green 

 and yellow cells is an inference from these few well-established 

 cases. 



2. Views of Previous Writers on the Green Cells 

 of Convoluta. 



Among the many green cells that have not been critically 

 examined^ those of Convoluta roscoffensis occupy an 

 exceptionally interesting position ; for whereas these green 

 cells resemble Protococcaceous algse in their chloroplast, 

 pyrenoid, and photosynthetic powers, they differ from all 

 true algfe and resemble animal cells in their lack of a 

 cellulose wall and in their supposed inability to survive the 

 death of the Convoluta, or to live Avhen isolated in a 

 hanging drop (Haberlandt, 1891). Experiment, and experi- 

 ment alone, can decide their true nature. 



Up to the present time no rigid experiments have been 

 made. Nevertheless Haberlandfc has elaborated an ingenious 

 hypothesis with a view of meeting the exigencies of the 

 case, and Georgevitch has propounded a perfectly distinct 

 suggestion on the basis of a few hatching experiments. 



Habei'landt's hypothesis is evidently based on the analogy 

 of chloroplast transmission in the development of plants. 

 The green cells of Convoluta are, he suggests, part and 

 parcel of the tissues of this animal, and develop from pre- 

 existing green cells of the previous generation. But this 

 has not always been so. Originally the green cells were 

 independent algse (as chloroplasts of plant cells have also 

 been supposed to be by Schimper, quoted by Haberlandt, 

 1891), and their present lack of cell-wall and their inability 

 tp lead an independent life are the result of their association 

 with Convoluta. Concomitantly Convoluta has given 

 up its active and carnivorous mode of life, and now depends 

 on the, green cells for its nutrition just as they depend on 

 Convoluta for tlieir very existence. 



