170 F. KEEBLE AND F. W. GAMBLE. 



containing a high percentage (15-50) of oxygen may be 

 evolved from the animals. Starch may be present in the 

 corpuscles. They have been shown to contain chlorophyll, 

 patent or masked by other pigment. Structurally the 

 chlorellfe resemble certain algal cells. A wall of cellulosic 

 or pectose substance, absent in some cases, may be present. 

 The corpuscles may contain a nucleus, a pyrenoid, and occa- 

 sionally an eye-spot. This circumstantial evidence is strong, 

 but cannot be said to amount to proof. 



Evidence of the origin of the green or brown cells to be 

 final must be of a like nature to that demanded by patholo- 

 gists in the case of a micro-organism suspected of pathogenic 

 properties ; the organism must be isolated in pure culture 

 and the infection-test applied. 



So in the cases of animals infected with green cells ; these 

 cells must be isolated, and, by introduction into the body of 

 an animal previously free from them, be shown to give rise to 

 the normal green animal. In other words, the final proof of 

 the algal nature of the green cells can be provided only by 

 the synthesis of the green organism from its algal and animal 

 components. This synthesis has not as yet been effected in 

 an indisputable manner in any single case. The green or 

 brown cells of Turbellaria, Coelenterates, or sponges have not 

 as yet been isolated and cultivated. 



Beijerinck (1890) and Entz (1881-1882), it is true, made 

 cultures of green hydra, but owing to the proneness of the 

 cultures to infection from within and from without both the 

 authors and their critics have regarded the results with sus- 

 picion, especially in view of the fact that attempts at synthesis 

 were unsuccessful. 



Among green protozoa two or three cases of alleged isola- 

 tion of the corpuscles have been recorded. By macerating 

 the bodies of Stcntor, Paramecium, and Frontonia, Famintzin 

 (1889-1891), Dantec (1892), and Dangeard (1900) have 

 obtained colonies of algie. The results are, however, some- 

 what discrepant, for whereas the first two authors regard the 

 alga of Piiramecium as a true chlorella, the third considers it 



