THE ORIGIN OF THE HUMAN BODY 293 



tigial rudiment, he is in open conflict with facts ; for the pineal 

 body i?, in reality, an endocrine gland generating and dis- 

 persing; a hormone, which is very important for the regulation 

 of growth in general and of sexual development in particular. 

 Hence this tiny organ in the diencephalic roof, no larger than 

 a grain of wheat, is not a functionless rudiment, but an im- 

 portant functioning organ of the cryptorhetic system. We 

 have no ground, therefore, on this score for inferring that our 

 pineal gland functioned in former ancestors as a median eye 

 comparable to that of the cyclops Polyphemus of Homeric 

 fame. 



In like manner, the pituitary body or hypophysis, which in 

 man is a small organ about the size of a cherry, situated at 

 the base of the brain, buried in the floor of the skull, and 

 lying just behind the optic chiasma, was formerly rated as a 

 rudimentary organ. It was, in fact, regarded as the vestigial 

 remnant of a former connection between the neural and ali- 

 mentary canals, reminiscent of the invertebrate stage. 'The 

 phylogenetic explanation of this organ generally accepted," 

 says Albert P. Mathews, "is that formerly the neural canal 

 connected at this point with the alimentary canal. A probable 

 and almost the only explanation of this, though an explana- 

 tion almost universally rejected by zoologists, is that of 

 Gaskell, who has maintained that the vertebrate alimentary 

 canal is a new structure, and that the old invertebrate canal 

 is the present neural canal. The infundibulum, on this view, 

 would correspond to the old invertebrate oesophagus, the ven- 

 tricle of the thalamus to the invertebrate stomach, and the 

 canal originally connected posteHorly with the anus. The 

 anterior lobe of the pituitary body could then correspond to 

 some glandular adjunct of the invertebrate canal, and the 

 nervous part to a portion of the original circumoesophageal 

 nervous ring of the invertebrates." ("Physiological Chemis- 

 try," 2nd ed., 1916, pp. 641, 642.) 



This elaborate piece of evolutionary contortion calls for no 

 comment here. We are only interested in the fact that this 



