This is the most effective example, but aware of other cases in which organisms not accept a "foreign order". Well-known blood group system is simple, and determining the blood group, you can almost always avoid the disintegration of red blood cells. Moreover, a person can be a blood transfusion chimpanzees respective group. But occasionally there are people with unique sets of blood factors that tie them to each other will not do. Insulin – the only effective remedy against diabetes differs relatively small species-specific, and therefore for the treatment of diabetics can use this protein isolated from the pancreases of cattle. But growth hormone – growth hormone – vidospetsifichen. For the treatment of dwarf growth in people want that kind of human growth hormone, which is released from the pituitary gland of dead people. It would seem that in lower organisms, an aversion to "someone else's order of" less.

Indeed, in fish and amphibians work out organ transplants between individuals of different species, and bovine growth hormone can stimulate the growth of trout. However, all this is artificial, created by the experiment situation. Again and again I repeat that the animals eating other animals or plants, beginning with the destruction of someone else's order. Food in their stomachs and intestines split special enzymes to simple substances that do not have species-specific. Thus, proteins cleaved to amino acids, complex carbohydrates such as starch and glycogen, – to monosaccharides, nucleic acids to nucleotides. According to the structure, for example, the amino acid glycine or phenylalanine is impossible to say whether it was obtained from the proteins of bovine meat, peas or chemist synthesized artificially.