592 
MR. E. C. BABER ON THE STRUCTURE OE THE THYROID GLAND. 
vesicle, which probably takes place in the following manner :—The vesicle being full 
of the viscid material is placed in the fresh state into alcohol. This coagulates the 
viscid material and causes it to shrink. When this takes place, however, it is 
necessary either that the walls of the vesicles should fall in, or that the space left 
between the epithelial wall and the coagulated content should be filled with some 
other fluid. It is probable that a clear fluid exudes from the epithelial cells in the 
form of a drop from each cell, producing the indentations above mentioned. This 
will also explain the occurrence of a pellucid appearance around the large round cells 
found in the viscid material in the Tortoise, which will be described further on (see 
Plate G8, fig. 11). For in the latter case when the viscid material contracts, fluid 
probably exudes from the large round cells, and as it escapes equally all round, in 
the case of one of these cells lying singly, the pellucid appearance is more or less 
spherical in shape, as shown in the figure. 
I have seen no sign of this homogeneous substance consisting of “ concentric layers,” 
or of its accumulating “layer upon layer,” as described by Zeiss. 
(b) Red blood-corpuscles .-—Pmcl bloocl-corpuscles are not uncommonly seen in the 
vesicles of the thyroid gland. They have been observed in the glands of Dogs (whose 
age ranged from 5 weeks to 7 or 8 years), in the glands of several Tortoises, and in 
the Conger Eel. The blood-corpuscles, which from their being situate in the homo¬ 
geneous material (colloid) above described had beyond all doubt entered the vesicles 
during life, are sometimes few in number, but at other times they completely Jill the 
vesicle. They either appear collected (or fused) into a ball in the centre, or are 
scattered throughout the contents of the vesicle (see Plate 68 , fig. 10, from the 
Tortoise). They are also frequently met with arranged in a layer close to the 
epithelial cells (see Plate 68, fig. 12, from the Dog). The corpuscles are observed 
in different stages of disintegration and decolonisation. In some instances in the 
thyroid gland of the Dog the epithelial wall of a vesicle containing red bloocl-corpuscles 
was seen to be studded with a quantity of minute yellow granules, no doubt due to the 
absorption of the colouring matter of the escaped red blood-corpuscles by the epithelial 
cells or inter-cellular reticulum. (Plate 69, fig. 13, 2 , 2 . & 3 , shows these granules in 
the epithelial wall of two vesicles containing red blood-corpuscles.) Colourless blood- 
corpuscles are sometimes observed in the cavity of the vesicles mixed with the 
coloured ones. 
In the ten Dogs examined, whose age varied from 5 weeks to 12 years, one or more 
vesicles containing red blood-corpuscles were found, with one exception, in all instances 
either in one or both glands. (These glands were all uninjected.) The exception was 
that of a Dog (female, aged 12 years) in which appearances rendered it very probable 
that there had been an escape of red blood-corpuscles, but this could not be ascertained 
for certain. 
In one gland of a Dog from this series (female, aged 7 or 8 years) a very large pro¬ 
portion of the vesicles contained red bloocl-corpuscles in greater or less number (see 
