42 SYMBIOGENESIS 



of alkaloid poisons, developed in self-protection by the plant, 

 and the appalling potency of their action upon animal 

 physiology. 



We may now return with clearer vision to Prof. Heebie's 

 exposition of Convoluted plant-animalism and try to under- 

 stand what really happens when, in certain circumstances, 

 C. paradoxa and, to a somew T hat less degree, C. roscoffensis, 

 exploit their coloured cells in a summary manner. The facts 

 are: 



In prolonged darkness the yellow-brown cells, once their reserves of 

 food-material have been extracted from them to meet the needs of the 

 animal, are digested wholesale by C. paradoxa. If the water in which 

 they are contained is altogether devoid of food supplies, the attack by 

 the animal on its coloured cells occurs all the sooner. Even in the light, 

 if external food supplies are withheld from C. paradoxa, a time comes 

 when, although the yellow-brown cells are supplying it with photo- 

 synthesised food-materials as fast as they can under the difficult 

 circumstances, it turns upon them killing and digesting the goose 

 which laid its golden eggs. 



Microscopic examination of animals kept in prolonged darkness 

 supplies evidence that the degeneration of the yellow-brown cells is not 

 a mere decay within the body, but is the result of a true process of 

 digestion exerted on them by the animal. 



It is interesting to observe, in this connection, that if animals are 

 brought, after a prolonged sojourn in darkness, into the light and 

 supplied with fresh sea-water, yellow-brown cells make their appearance 

 again in the bodies. As they grow and increase in numbers, the animals 

 also begin again to grow. 



So also in the case of C. roscoffensis, if the green cells fail to make 

 their appearance in the body, the animals remain of microscopic size. 

 If, on the other hand, the green cells appear, increase and multiply 

 to form the characteristic green tissue, the animals begin to grow rapidly. 



Thus in various ways it has been demonstrated that C. roscoffensis 

 and C. paradoxa depend for their food on their coloured cells. Without 

 them they fail to grow. 



It is evident that the coloured cells are of enormous 

 importance in the physiological economy of our plant- 

 animals. In partial, in retrograde, or in genuine bio-economic 

 symbiosis the wonderful properties and gifts of the plant 



