208 QUARTERLY CHRONICLE. 
ture of the thyroid gland, he says, still remains in some measure 
a subject of dispute. In the writings of anatomists the most 
contradictory views are met with respecting the essential 
elements of the organ, namely, the vesicles ; and especially 
are the opinions of enquirers divided with regard to the 
secretion of the gland, viz., the so-termed colloid substance ; 
some regarding this as a normal product, and others as a patho- 
logical one. The size of the vesicles, which depend upon the 
greater or less accumulation within them of the colloid 
substance, is regarded by many as a diagnostic character of a 
normal or pathological condition of the organ. These and 
similar differences of opinion have induced the author to 
think that it would be useful to submit the structure of the 
gland to further comparative investigation. With this view 
he has examined it in man, dog, cat, rabbit, hedgehog, 
mouse, rat, sheep, ox, calf, pig, jackal, fowl, and raven; in 
all of which the structure of the gland is the same, consisting, 
as is known, of vesicles which constitute the essential element, 
connective tissue, blood, lymphatic vessels, and nerves. 
As regards the structure of the vesicles, the author has 
never been able to perceive any memérana propria, as described 
by Kolliker, and denied by Frey, Hessling, and others ; 
whilst some assert that the membrana propria is lined with 
an epithelium, the existence of which is disputed by others, 
as Eulenberg and Ecker. 
Though unable to find any membrana propria, Dr. Pere- 
meschko has satisfied himself of the presence of an epithelial 
lining, which rests immediately upon the surrounding homo- 
geneous, membranous layer, formed of condensed connective 
tissue. The epithelial cells are firmly attached to each 
other, and but loosely to the connective tissue layer, so that 
in some’ instances the entire vesicle may, as it were, be enu- 
cleated. He finds the vesicles to increase in size in proportion 
to age, and consequently that what has in some instances been 
regarded as a pathological enlargement, may have been 
merely due to the advanced age of the animal. 
The paper is a very interesting contribution to our know- 
ledge of the thyroid gland. : 
V. “ Contributions on the Anatomy and Classification of the 
Holothuriade,” by Emil Senka.—After a short but very com- 
prehensive account of the anatomical structure of the Holothu- 
riad, which leaves little to be desired, the greater part of this 
very valuable paper is occupied with a systematic classifica- 
tion and description of the species contained in the rich 
collection brought together by Professor Keferstein, in the 
Zoological Museum of Gottingen ; and the still richer stores of 
