270 



DAVID MAKINE 



the lung than any other tissue. In- 

 deed, there are many interesting 

 embryological, anatomical, physio- 

 logical and pathological relations 

 between the thyroid and the lung 

 which have added much to our 

 knowledge of the physiology of in- 

 ter-relationships. The thyroid tis- 

 sue is one of the most labile tissues 

 in the body, capable of rapid over- 

 growth and of rapid involution. 

 Its wide range or cycle of morpho- 

 logical changes makes it possible to 

 detect easily morphological changes 

 which, if interpreted in terms of 

 function, are but little removed 

 from normal, but which, if inter- 

 preted in relation to similar mor- 

 phological changes of other body tissues less well endowed with the 

 capacity for growth, have frequently resulted in too great importance 

 being attached to the pathological anatomy. 



The outline of human thyvoid changes given at the beginning of this 

 article combines in sequential order so far as possible', the physiological 



Fig. 3. Cross section of the endostyle 

 organ of Ammocoetes branchialis taken 

 through its duct. (After Marine, Johns 

 Hopkins Hosp. Bull., 1913: 24.) 



Fig. 4. Cross section of the thyroid area of Ammoccetes branchialis in the last 

 stages of metamorphosis showing well formed thyroid alveoli together with consid- 

 erable unabsorbed cell detritus and pigment from the old endostyle organ. (After 

 Marine, Johns Hopkins Hosp. Bull., 1913: 24.) 



