1881.] On the Minute Structure of the Thyroid Gland. 279 



January 6, 1881. 



THE PRESIDENT, followed by General STRACHEY, V.P., 

 in the Chair. 



The Presents received were laid on the table, and thanks ordered 

 for them. 



The following Papers were read : — 



I. " Researches on the Minute Structure of the Thyroid Gland." 

 By E. Cresswell Baber, M.B. Lond. Communicated by 

 E. E. Klein, M.D., F.R.S. Received November 25, 1880. 



(Abstract.) 



This research, which is a continuation of one previously com- 

 municated to the Society,* is based on an examination of this organ in 

 the dog, cat, horse, rabbit, ox, sheep, seal, pigeon, fowl, rook, tortoise, 

 frog, skate, and conger-eel. The research has been carried on under 

 the direction of Dr. Klein, and the following are the chief conclasions 

 which have been arrived at : — 



. (1.) Vesicles. — Although branched vesicles may be present, the gland- 

 vesicles in the thyroid of adult animals, according to the author's 

 observations, form closed cavities, which are not in communication 

 with one another to any extent. Much-branched vesicles, which have 

 been observed in the glands of young dogs, are considered merely as 

 forming a stage in the growth of the gland, and as indicating that an 

 increase in the number of vesicles is taking place. In the thyroid 

 gland of the conger-eel, small vesicles (containing colloid) are fre- 

 quently observed in the walls of large ones, and from the appearances 

 t hey present it is probable that the walls separating the cavities of the 

 large and small vesicles sometimes become flattened out and give way, 

 allowing the contents of the two vesicles to commingle. 



(2.) Epithelium, Reticulum, and Basement-Membrane. — Whilst the 

 shape of the epithelial cells of the vesicles varies much in different 

 animals, the general tendency of these cells throughout the vertebrate 

 series, as far as examined, is to the columnar form. A delicate reti- 

 culum (as described by Zeiss) has been observed amongst the epithelial 

 cells. In a profile view of the epithelium club-shaped cells are also 

 often seen, which are probably indicative of more or less branched 

 cells, situate in the reticulum. The only form of basement-membrane 



* " Phil. Trans.," vol. 166, p. 557. 



VOL. XXXI. 



