The first lymph glands in rabbit and human embryos

111 IS!)Ci Syscr stated that tlic lyiiipli glatids in sliecp a i d cow enibryos arise froiii a plexus of lymphatic vessels.' "The connectirctissuc between the lymphatic!vessels of the plcsns has at first a trabecular arrangement, but later one or iiiore coin1)aet masses or islands are foriiied within it.From the Legiiiiiiiig, the conncctiw tissuc which iiiakes the trabccnlae, or niasws, is ~iarrowcr iiieshed than that which surrouiids it, and contaiiis niaiiy blood vcsscls."However, he adds: "There can be 110 doubt that there are inaiiy plexiis forinations in embryonic tissue, hariiig exactly the appearance uf those from which lymph glands arise, which simply degenerate."Kliiig, in 1901, emphasizeil the iiuportance of the plexus s t a y aiid modelled the lyniphoid trabeculae.2Although they connect with one another so as to form a continuous mass, his model has "an extremely irregular appcarancc."I t shows that these structured have little resemblance to the futnre glands.Kliiig stated that from such a general mass portions were separated by constriction to foriii the basis for individual gla~ids.Rut "Iyniph glaiids which have an isolated position appear froni the first as solitary foriliatioils ; each one arises independently."A year later Miss Sabin wrote:" "All of the iiorlrs of the early 'Saser, F.