LYMPHATICS, ETC., OF THYROID GLAND OF THE DOG. 205 



connective tissue investing the gland, from which strong 

 trabeculse pass inwards, dividing the gland into lobes, and 

 from these again finer septa originate, which subdivide the 

 lobes into lobules. In this way the thyroid gland of man " is 

 divided into primary and secondary segments, the line of 

 division between which is recognisable by slight furrows" 

 (Verson). The connective tissue lying between the several 

 gland-vesicles is, according to the same author, very sparing 

 in quantity, and sometimes even it is difficult to discover 

 between the walls of contiguous vesicles a few fibres accom- 

 panying the capillaries. Henle finds the vesicles partly 

 separated by fine connective-tissue septa, and partly in direct 

 contact with one another. The gland- vesicles (Driiseti- 

 hlaschen, Kolliker) are described as closed globular bodies, 

 consisting of a very fine homogeneous membrane {memhrana 

 propria), lined by a single layer of epithelial cells (Kolliker, 

 Henle, Verson). Frey does not believe in the presence of a 

 vienibrana propria. The epithelial cells are described by 

 Henle as flattened cells, containing circular nuclei, and re- 

 sembling a layer of epithelium. According to Kolliker they 

 are polygonal, finely granular, transparent cells, each with 

 a single nucleus. Frey, again, alludes to them as flattened, 

 cylindrical, nucleated cells. Finally, Verson lays stress on 

 the fact that the cells in the fresh condition are always 

 somewhat higher than broad. 



The cavity of the vesicle is described as occupied by a clear 

 viscid fluid (Kolliker, Frey), slightly tinged with yellow, and 

 containing much albumin (Kolliker) Henle speaks of the 

 contents as clear and becoming converted by the action of 

 alcohol into a firm, somewhat shrunken coagulum. 



The lymphatics of this organ have been last studied by 

 Frey, who gives the following account of them, as quoted by 

 Henle [loc. cit.) : — "The large lymphatics covering the cap- 

 sule of the thyroid gland take their origin from a rounded 

 network which surrounds the secondary lobules. From these 

 there branch off" finer arborescent canals for the primary lobules, 

 to surround them with perfect rings or with arches more or 

 less complete. From these, again, a few finer canals dip 

 down among the individual vesicles, and end in blind ex- 

 tremities." Frey himself (op. cit.) describes the lymphatics 

 as quoted above by Henle, excepting that he does not confirm 

 the statement of their ending in blind extremities. 



The present research was undertaken with the object of 

 investigating the lymphatics of this organ ; in the course of 

 it, however, it became necessary to study carefully the vesi- 

 cular and intervesicular tissue of the gland, and in so doing 



