Vol. XIII. November, igoy. No. 6. 



BIOLOGICAL BULLETIN 



ARTIFICIAL REMOVAL OF THE GREEN 

 BODIES OF HYDRA VIRIDIS. 



D. D. WHITNEY. 



Whether the green bodies in hydras are infecting algae or prod- 

 ucts of their own metabolism has been long disputed. I have dis- 

 covered a method by which they may be removed and the hydras 

 continue to live nevertheless and to multiply. 



Semper suggested that these green bodies in Hydra viridis 

 might be algse. A little later Brandt made a careful study of 

 them and concluded that they are algae which probably live para- 

 sitically in the endoderm cells of the hydra. 



At the same time Lankester also studied these green bodies. 

 He said : " It appears to me that an examination of the green 

 colored corpuscles of Hydra demonstrates those corpuscles to be 

 similar in nature to the chlorophyll bodies of green plants, and 

 that there is no more reason to regard them as symbiotic algae 

 than there is to regard the green corpuscles in the leaf of a but- 

 tercup as such." 



Sallitt examined the green bodies in several species of Proto- 

 zoa and found them to be identical with the green bodies of 

 Hydra and Spongilla. This uniformity of the green bodies in 

 different animals and their similarity to the chloroplasts of plants 

 led to the belief on the part of a few zoologists that the green 

 bodies in animals and plants are identical and probably have 

 the same function in both kinds of organisms. 



Beyerinck in 1890 isolated the green bodies from Hydra viri- 

 dis and succeeded in making pure cultures of them in an artificial 

 medium. This demonstrated that the green bodies were dif- 

 ferent from the chloroplasts of plants. He, moreover, identified 

 them with the alga, Chlorella vulgaris. 



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