MINOT : SINUSOIDAL CIRCULATION. 
209 
vessels “lacunare Capillaren,” which name is synonymous with 
sinusoids. This organization is not constant even in the sheep, 
since the organ in many cases contains some connective tissue, 
which may in part form thin layers between the blood vessels and 
the parenchyma, and in part fill spaces between the parenchymal 
trabeculae. But the connective tissue is always small in amount 
(Schaper, l. c., p. 253), so that the sinusoidal type is essentially 
preserved. This organ seems to me peculiarly instructive as regards 
the relation of sinusoids to connective tissue, a subject concerning 
which some brief general remarks may be found towards the close 
of this article. 
That the human parathyroid has a similar arrangement of the 
blood vessels has been recorded by L. Schreiber, ’98.1. Thus, for 
example, in speaking of the 4J months foetus, he says, p. 719, 
that the blood vessels “ zum Theil in den Bindegewebssepten 
verlaufen, zum Tlieil liegen ilire Endothelien ohne jegliclie binde- 
gewebige Umscheidung direkt den Epithelzellen an.” His figures 
show this relation and also that the vessels are considerably wider 
than true capillaries. D. A. Welsh, ’98.1, has also studied the 
human parathyroid, but as he had only histologically poor material, 
his observations provide no available knowledge concerning our 
special enquiry. 
7. Carotid gland. In regard to the minute structure of this 
gland our knowledge is derived chiefly from the investigations of 
Paltauf, ’91.1, and Schaper, ’92.1. The internal circulation of the 
organ occurs in endothelial blood spaces, which are wider and have 
more frequent anastomoses than the ordinary capillaries. Between 
these blood spaces (and, except for a little fibrillar tissue), filling 
the intervals, lies the parenchyma of the organ, which consists of a 
cellular reticulum, in which are imbedded the relatively large par¬ 
enchymal cells proper, and also nerve fibres and an occasional nerve 
cell. The descriptions of Schaper and his figures, especially Fig. 2, 
render it probable that the circulation is sinusoidal, but on this 
point I wish expressly to refrain from any positive assertion. 
8. Coccygeal gland. According to J. II. Jakobsson, ’98.1, 
the organ has wide blood vessels with merely endothelial walls, 
close about which are packed the crowded parenchymal cells. The 
cells form perivascular layers, and consequently cords, as it were, 
which are separated from one another by thick connective tissue 
septa. It seems, therefore, that the organ has sinusoids, and not 
capillaries. 
