CAUSE OF HEREDITY 307 



purpose and it is put together by someone. It does not 

 come together by chance. Mr. Walker calls our atten- 

 tion to a peculiar plant and worm living together in part- 

 nership as one individual. The plant lives inside of the 

 worm and inside of this worm the plant makes food and 

 building material for both. He states : "A still more 

 remarkable case is afforded by a low form of worm (con- 

 voleta roscoffensis) which lives symbiotically with green 

 algae. The algae appears to form a special assimilation 

 tissue within the worm enabling it to live like a green 

 plant. The worms are elongated and colored green and 

 at Roscoff live in the sandy tide pools fully exposed to 

 the sun's rays, looking like a mass of floating weed upon 

 the surface of the water. Now the stomach and indeed 

 the whole of the alimentary apparatus has disappeared 

 in the worm and it lives exclusively upon carbohydrates 

 formed within its body by the algae. The algae has un- 

 dergone most profound changes. It has lost its mem- 

 brane, thus allowing its secretions and excretions to pass 

 freely among the cells of the worm and it cannot live 

 independently. If the worm dies the algae contained in 

 it die. All the allied forms of this worm seek the dark 

 and live concealed under stones and vegetation and they 

 are carnivorous. Convoluta, however, being dependent 

 upon the well being of the algae for its nourishment 

 seeks the sunlight and the surface of the water. The 

 sunlight is necessary to the growth and metabolism in 

 the alga, which in its turn supplies food to the worm, 

 which has cea'sed to be carnivorous. The two forms are 

 thus absolutely dependent upon each other and incapable 

 of living apart." 



I am quite certain that Mr. Walker and others who 

 have examined this creature are mistaken in reference 

 to the facts. I think it will be found upon further ex- 



