190 JEREMIAH S. FERGUSON 



Bits of thyroid tissue of inconstant form or location are occa- 

 sionally separated from the body of the gland by narrow partitions 

 of connective tissue; they are most frequently found near the 

 border of the gland or adjoining an area in which the thyroid sub- 

 stance is deficient. Since they possess no constant relation 

 to the vascular supply, the detached masses can not correspond in 

 any sense to true anatomical lobules. The arteries branch irregu- 

 larly, for the most part after a somewhat dicotymous fashion 

 (fig. 12), the arterial twigs passing off at acute angles. Partially 

 injected specimens in which the injection fluid has passed through 

 the arteries but has not penetrated in quantity into the veins 



Fig. 12. Terminal divisions of the thyroid artery. The area occupied by 

 injected capillaries, "venae lymphaticae," directly connected with each terminal 

 arteriole is roughly indicated by the dotted lines. 



show areas of injected capillaries surrounding the terminal arteri- 

 oles (fig. 12), but the extent of these injected areas and their 

 relation to the artery seems to be dependent rather on the pressure 

 of the injection than on any constant or characteristic relation to 

 the vascular system. I can not recognize any probable vascular 

 or anatomical unit which might in any sense serve as an ana- 

 tomical lobule or structural unit, as described for various other 

 glands by Born, Mall and others. 



In Raia the occurrence of partially detached groups of thyroid 

 follicles is more frequent than in the other species, but the number 

 of such groups present in a gland varies from two or three to a 

 score or more. The groups are outlined by connective tissue in 



