Abstract

Animals and plants can be classified into three distinct groups according to their pH- and pO-values and the ratios of inorganic ion concentrations and organic molecule concentrations in their intracellular or extracellular saps . The origin of these types could be sought in the evolutionary change from aquatic to terrestrial environment. The widespread existence of these types in nature enables a direct comparison between the physicochemical composition of consumer and its producer. An example of such relationship was found in the order Hemiptera. No symbiosis exists when the consumer and producer belong to the same physicochemical type. On the other hand, if the types differ, extra- or intracellular symbiosis are usually found to exist. The conclusion is drawn that endosysmbiosis provides means for the compensation of this difference