Studien über die Entwicklung der Lymphdrüsen beim Menschen. 979 
dem im letzterwähnten Stadium überein. Ein Sinusretikulum 
war nun aufgetreten. Bei einem 7 Monate alten Fötus war ein 
deutliches Hilusstroma entwickelt, und bei dem neugeborenen 
_Kinde war das Bild ungefähr dasselbe wie beim Erwachsenen. 
Die Entwicklung des Trabekelwerkes konnte er nicht verfolgen. 
Conil (1890) fand Lymphdrüsenanlagen erst bei einem 
41/2 Monate alten menschlichen Embryo. 
Gulland (1894), dessen Arbeit die vollständigste ist, die 
wir bisher auf diesem Gebiete besitzen, ist betrefis der Punkte, 
die meine Untersuchung berühren, zu folgenden Resultaten 
gekommen: 
„In very young mammalian embryos there are no lymphatic vessels. 
Lymphatic vessels are first observed in a sheep fetus, 1'/ in. long, and 
they appear before there is any trace of lymphatic glands in the body. 
The connective tissue when they appear is already distinctly fibrillated, and 
the vessels arise by dilatation of preexisting connective tissue spaces in the 
line of the greatest Ilymph flow. Part of the fibres or membranes lining 
these spaces remain as the wall of the Iymphatic vessel, part are ruptured 
or absorbed; the nuclei of the connective tissue remain as the nuclei of the 
vascular endothelium. — — — 
The primary Iymphatic glands are those in the neck, groin, and 
at the root of the mesentery: these glands are the first to develop, and are 
all fully developed in fetal life. 
The secondary lymphatic glands are those at the bend of the 
elbow, in the popliteal space, in the mesentery, round the aorta and iliac 
arteries, etc., and are developed in some animals in fetal life, in others not 
till after birth, and sometimes imperfectly even in the adult. 
The Zertiary Iymphatic glands are formed in adult life on some 
special occasion, during the exceptional activity of some organ, or in patho- 
logical conditions. 
Primary lymph glands all appear at points towards which numbers 
of Iymph vessels converge, and where they meet by anastomosing to form 
a plexus; these plexuses are all situated near large arteries, and are well 
supplied with branches from them. 
The Zymph vessels of this plexus do not form the gland, though 
some remain to form the external sinus, others as the afferent and efferent 
vessels. The gland arises from nodules of connective tissue, surrounded by 
the plexus, traversed by an artery or running near an artery, in which the 
formation of capillary branches of the artery goes on rapidly. — — — 
The external sinus arises from the Iymphatics of the plexus which 
pass round the nodule. The septa between them are thinned by the 
functional dilatation of the vessels, till only a few are left; one main bridge 
carries the blood vessels. Most of the numerous delicate trabecule in the 
