10 DEVELOPMENT OF THE SYSTEMIC LYMPHATIC VESSELS 



our knowledge of the genesis of the mammahan lymphatic 

 system. 



The results so far obtained, and the views based thereon, may, 

 with inclusion of the older w^ork on the subject of vertebrate 

 lymphatic development in general, be briefly summed up as 

 follows in the form of short theoretic statements: 



I. The lymphatic system is developed independently of the 

 blood-vascular system. It is formed by the confluence of inde- 

 pendently developed mesenchymal spaces, and, in case of the 

 avian thoracic duct, by canalization of preformed sohd strands 

 of differentiated mesenchyme."^' ''•^ 



The works of Brachet and the combined researches of Brachet 

 and Swaen,* in their relation to the interpretation of lymphatic 

 development, also support the independent origin of the lymph- 

 atic system from the mesenchyme. 



The interesting observations of Marcus on the development and 

 organization of the lymphatic system in Hypogeophis^ place the 

 conclusions of this investigator in regard to the genesis of lym- 

 phatic structures in this general division, wdth the addition of the 

 coiK'option of the coelomata as primary lymphatic spaces (vide 

 infra, pp. 25 and 26), and the phylogenetic derivation of the 

 |)('riplieral lymphatic system from the same. 



Miyiljic: "Ueber ein Canalsystem im Mesoderm von Huhneienibryonen." 

 Arch, fiir Ariat. und Phya., Anat. Abth., 1880, s. 320. "Untersuchungen liber 

 (lie Kntwicklung dcs Lyinphsystem.s beim Hiihnerembryo." Arch. f. Anat. u. 

 I'htjH., Anat. Abth., ISsV, s. .W. 



• I,. Sala: ".Siillo .^'viluppo dci ciiori lini'atici c dci dotti toraeici uell' cnibryouc 

 di polio," Riccrche fatta nel Laboratorio di Anatomia Normale della R. Univ. 

 di Roma, vol. vii, p. 2(53-209, April. 1900. 



'CI. Lovfll (Julland: ""Plic DcvcIoijiihwiI of Lyinphul ii- (daiids". Jour. Path. 

 iitiil Unci , vol. ii, 1894, j)p. U7-48.'). 



\ l'i:irlicl, " Hcclicrclics sur lo develoi)]). du coeiir, dos j)iciiiicrs vaisseaux 

 ••I clii .sarin '-lirz h'.s ainpliibiciis iirodeles," Arch, d'anat. microsco pique, ii, 1898. 

 ■'Rc-rluTcltcs .sur I'oriKiiic dc rai)p;iroil vasciilairo sangiiin rlioz los amphibicns," 

 .Arch, dc liiohgic, xix, 1903. 



\. Swufii ft .\. Brarliel. "lOludf sur les premiers phases du drveMopj). des 

 ..iKaii.s ({('•rivrs du iM.'s.iblasI clicz ics poissons t<'>leostiens." Arch, dc Biologic, 

 xvi, 1S99-19()(). 



• H. Marcus, " licitriige zur Kcimtnis dcr (iymnophionen; II. Ueber interseg- 

 nieiitalc Lymphherzen, ncbst liemerkungen iiber das T.yiTii)lisystem.'-' .Morphol. 

 Jnhrhuch, Hd. xxxviii, Heft 4. 1908. 



