6 INTRODUCTION 



less restraint than in one of the current publications. I have 

 been led to the undertaking largely by my conviction of the value 

 of the work which has been done within the last decade in this 

 field by American investigators. The development of the lym- 

 phatic system is one of the very few broad morphological 

 problems as yet incompletely solved, and I believe that the pains- 

 taking, able and conscientious work of the relatively large num- 

 ber of interested investigators of the subject in this country will 

 eventually furnish a satisfactory answer to the question, as a 

 national contribution to the advancement of anatomical science. 

 I have been obliged to differ, on the basis of my own investi- 

 gations, from the conclusions reached by most of my American 

 colleagues. I hence welcome the opportunity of placing my results 

 fully on record, in such a manner that they can be readily examined 

 and verified, if correct, or refuted, if found to be erroneous. In 

 carrying out this purpose it is of course necessary, in order to 

 avoid repetition and economize space, to simply refer to those 

 parts of the subject which have been already fully covered in 

 the existing publications, and to include these articles as part 

 of the entire record. The main problem then is narrowed down 

 to the developmental history of the mammalian systemic 

 lymphatic channels, as distinguished from the jugular lymph 

 sacs, or other homologous structures of like origin and equivalent 

 functional significance, wherever situated. 



The proposed series of publications will include the following 

 topics in the order given: 



Part I. The development of the systemic lymphatic vessels in 

 their relation to the blood vascular system. 



Part II. The development of the preazygos and azygos segments 

 of the thoracic ducts. 



Part III. The development of the visceral lymphatic drainage, 

 and especially of the lymphatics of the abdominal cavity; the forma- 

 tion of the receptaculum, and of the postazygos segment of the thor- 

 acic ducts, as well as the lymphatic return from the pelvic and caudal 

 regions and from the posterior extremity. 



