The Origin and Development of the Lymphatic System. 9 



to study lymphatics in the adult liver (17) and in bone (18) by means 

 of injection, and in 1880 (19) he described studies of a system of 

 canals which he could inject in mesoderm of three-day chick embryos. 

 These injections, which can be easily repeated, giving the exact pat- 

 terns of Budge, were really made into the extraembryonic coelom, as 

 has been shown by Mall (81) and myself (129), and have nothing to 

 do with the lymphatics. They are not, as Budge himself noted, lined 

 by endothelium ; indeed Budge himself was most cautious in his inter- 

 pretation, for he says (19, p. 325), "Mit Absicht habe ich den Aus- 

 druck Lymphgefassystem fiir das eben beschriebene Canalsystem 

 vermieden, weil mir hierfiir noch nicht Ajnhaltspunkte genug gewon- 

 nen zu sein scheinen. Und doch liegt der Gedanke hieran nahe." In 

 1881 Budge (20) announced the important discovery that there was 

 a plexus of lymphatic vessels accompanying the allantoic arteries of 

 chicks easily injected from the sixteenth to the eighteenth day of incu- 

 bation, and that these injections ran to the thoracic duct. The next 

 year (21) in a fuller paper he described that these allantoic lymph- 

 atics not only entered the thoracic duct but drained into the posterior 

 lymph heart, which played a great role in relation to the allantois. 

 He injected the lymph heart through the allantoic vessels by the tenth 

 day, and noted that the posterior lymph heart was preceded, as seen 

 in the living chick (8 to 12 days), by veins, and that subsequently the 

 lymph heart appeared, which could be distinguished by the fact that it 

 pulsated with a different rhythm from the blood vessels. After 

 Budge's death his work was brought together by His (22) and formu- 

 lated somewhat in this manner : There are two lymphatic systems, a 

 transitory and a permanent system, the first consisting of spaces in the 

 extraembryonal membranes analogous to the coelom and found only in 

 early stages. The second, consisting, of the true endothelial-lined 

 vessels which accompany blood vessels — which Budge so successfully 

 injected. The thoracic duct he thought arose from the first system and 

 was the only permanent part of the first system. Thus Budge's work, 

 which was a reaching out into a dark field and had genuine important 

 discoveries, was in line with the prevailing theory that lymphatics are 

 related to tissue spaces, and introduced a misleading conception that 

 lymphatics form after the same manner as the coelom and indeed in 

 part as an extension of the ccelom as far as the primativ system and 

 thoracic duct are concerned. 



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