376 B. F. KINGSBURY 



thyreoids, thymus — and this it is that causes the inclusion 

 of the problem of the endocrine organ group as a subject of 

 discussion in this paper. The common origin of these organs 

 from the pharynx led Kranichfeld to assume that the pharyn- 

 geal epithelium is from the beginning and primitively 'internally 

 secreting' (which it may well be) and that its epithelial deriva- 

 tives but continue an activity that was common to them while 

 still a part of the embryonic pharynx. He brings in support 

 of this \dew no evidence, direct or indirect, and several objections 

 might be raised in criticism. I believe it is possible, however, to 

 view the pharyngeal derivatives, in common with the other en- 

 docrine organs, quite differently. 



It is, of course, a matter of history that many of these organs 

 have been frequently regarded as vestigial structures remnants 

 of organs of past usefulness, but now obsolete and without 

 'function.' With the increase in knowledge of internal secre- 

 tion, the pendulum swung the other way and there is frequently 

 met a tendency to den}^ altogether the existence of anything 

 'vestigial,' or without function, in the body. It becomes, how- 

 ever, largely a matter of definition of S^stigial' and 'function.' 

 As far as the endocrine organs are concerned, it is quite pos- 

 sible that both views are correct; that they are, in a sense and 

 from one point of view, vestigial structures and that they are 

 peculiarly 'internally secreting;' further, even that they owe 

 their significance as endocrine organs to their quasi vestigial 

 nature. In the case of many of them it is clear that they arose 

 either in the individual or in the race, out of structures mor- 

 phologically quite different and physiologically of a distinct adap- 

 tative value, while the designation as organ or gland frequently 

 becomes difficult. 



The corpus luteum arises out of the wall of the Graafian fol- 

 licle after its collapse, by what might be called a reaction of 

 degeneration accompanied by growth; has, it would seem, an 

 unquestioned influence, particularly upon the uterus through 

 its metabolism; it finally degenerates. It might be termed a 

 'gland,' periodically developed and disappearing within the 

 individual lifetime. The pineal bod}^ or gland develops out 



