EXTRACT XLIV. 



ON THE CAUSATION AND EVOLUTION OF SOME CASES 

 OF GOITRE, WITH OBSERVATIONS ON CRETINISM, 

 MYXCEDEMA, ETC. 



WHEN discussing the methods of disposal of the pituitary 

 secretion or excretion by the tonsillo-glossal excretory 

 mechanism in a former study, we became possessed of the 

 idea that in certain conditions of post-natal and adult 

 existence favourable or conducive to the survival or 

 renewal of the patency of pre-natal gland ducts, we had 

 in view a possible cause of the origin of some diseases 

 affecting ductless glands of which the thyroid may be 

 regarded as a typical example. This gland, during its 

 embryonic and foetal stages of existence, undergoes many 

 evolutionary and developmental changes in the arrange- 

 ments of its parts preparatory to their permanent associa- 

 tion as component lobes or divisions of the same glandular 

 organ, its two lateral lobes undergoing a separate or 

 unilateral development, and ultimately uniting with and 

 merging into each other through the central lobe or 

 isthmus, which is the terminal inferior extremity of the 

 duct known as the glosso-thyroid or thyro-glossal, whose 

 superior extremity begins at or opens through or by the. 

 foramen caecum on the posterior aspect of the upper surface 

 of the tongue, and "hereby hangs a tale." Anatomically 

 speaking, no duct can open by or through a foramen 

 c<cum, and hence we must believe that the thyro-glossal 

 duct is no exception to the rule. Therefore, the thyro- 

 glossal duct gave passage in its pre-natal or foetal con- 



