50 SYMBIOGENES1S 



instead. Euglena neither appropriates nor swallows its plant 

 cells. It has, on the contrary, struck up a genuine domestic 

 symbiosis between plant and animal cells. Such a genuine 

 arrangement contains the promise of a fruitful symbiogenesis 

 and subsequent fruitful stages of biological symbiosis. 



If in course of evolution the vicarious plants have evolved 

 secrets of manufactures not possessed by the animals, the latter 

 need not be the poorer for this reciprocal differentiation, 

 so long as they remain tolerably symbiotic in their behaviour. 

 Just as the actual position of a plant in the scale of evolution 

 is in accordance with its bio-economic productiveness, so, 

 broadly speaking, the actual position of an animal is in 

 accordance with its relations to the plant kingdom. As a 

 general principle, one may lay it down that cultivators 

 (" arare " Aryans among humans) must always in the long 

 run rise superior to depredators (hunters). 



The cultivator (except in " Raub-bau ") takes for his 

 pains no more than is compatible with the powers of the 

 cultivated species ; nor are they the poorer for being stripped 

 of their surplusage. Plants, like bees, seem to resent (if the 

 term be permissible) only extreme degrees of depredation in 

 their cultivators. (Prof. Eimer reports that: "According to 

 statements which seem to me perfectly reliable, bee-keepers 

 who allowed their bees no peace and continually took from 

 them the last drop of their honey, have sometimes been 

 suddenly attacked by them, apparently with a common pur- 

 pose, and been very severely injured by them.") 



The powers of production on the part of the photo- 

 synthetic plant are enormous, and the plant is also in this 

 respect a marvel of efficiency. 



" In the formation of carbohydrates, for example," says 

 Prof. A. B. Macallum, "the chlorophyll-holding cell makes use 

 of processes of the most speedy and effective character. Nature 

 works unerringly, unfalteringly, with an amazing economy of 

 material and energy." 



