102- MAN* --AN ADAPTIVE MECHANISM 



local resistance, and may cause appendicitis and peri- 

 tonitis. Thus, syphilis and gonorrhea may have origi- 

 nated from earlier harmless species of spirochetce and 

 gonococci, which at first subsisted normally upon the 

 specific secretions of the genitalia, but later through 

 adaptive changes became abnormal and harmful. 

 Notable evidence of the adaptive origin of gonorrhea 

 and syphilis is offered by Ehrlich in his observation 

 that the spirochetse grow best in a culture made from 

 the testicles of the higher apes. It is also noteworthy 

 that no corresponding diseases exist among animals 

 which conjugate only at rutting time. To evolve 

 a species of microorganism adapted to a certain food 

 supply peculiar to one region of the body, would re- 

 quire, as a basis for that evolution, a constant, or nearly 

 constant, supply of that food. 



Phagocytosis 



As the bacteria met the first adaptive attack of 

 the amoeba by evolving poisonous secretions, so the 

 higher organism meets the attempt of bacteria to 

 overcome its equilibrium by evolving substances which 

 destroy or neutralize the power of the invaders. The 

 most primitive type of these chemical defense mecha- 

 nisms to be found in higher organisms is an exact analogy 

 of the nutritive process by which the amoeba envelops 

 and digests the bacteria in its environment. This is 

 the action of the phagocytes, amoeboid-like bodies, 

 which move from place to place in the organism and 

 envelop and digest certain substances alien to the 

 organism. The specific habitat of these peripatetic 

 guardians is in the blood and the lymph. Because of 



