RELATION OF LYMPHATIC TO BLOOD-VASCULAR SYSTEM 15 



Cat, which animal, by reason of its clear-cut type of venous 

 development, 23 and the great range of its adult venous varia- 

 tion, 24 * 25 seemed to me to offer the best opportunity of viewing 

 the problem of mammalian lymphatic development both from 

 the standpoint of its normal course in a representative form, and 

 with reference to the variant conditions imposed upon it by 

 correlated variants in the organization of the main systemic veins. 



I have been further influenced in my selection of the cat 

 for special and detailed study by the fact that in my experience 

 the embryos of this carnivore offer uniformly histological pictures 

 of lymphatic ontogenesis which are far more definite, clean-cut 

 and conclusive than those obtained in ungulate, rodent or marsu- 

 pial embryos. I believe that the cat is the only known available 

 mammal in which the facts of systemic lymphatic development, 

 as set forth in the following pages, could have been definitely 

 ascertained. Guided by the clue thus furnished, it is not diffi- 

 cult to determine, by comparison, the existence of absolutely 

 corresponding developmental conditions in the embryos of the 

 pig, rat, rabbit, and opposum. But in none of these forms are 

 the typical genetic stages as clearly marked and the tissues as 

 definitely differentiated as in the cat. 



The investigation of mammalian lymphatic development 

 divides itself naturally, in accordance with the postulates of the 

 genetic theory above advanced (VI), into three separate and 

 distinct main parts: 



(1) The development and adult anatomy of the jugular 

 lymph sacs. 



(2) The development and adult anatomy of the general 

 systemic lymphatic vessels. 



23 G. 8. Huntington and C. F. W. McClure : "The Development of the Postcava 

 and Tributaries in the Domestic Cat." Am. Jour. Anat., vol. vi, 1907, Abstr. 

 Anat. Record, vol. i. 



24 VVm. Darrach: "Variations of the Postcava and its Tributaries in 605 Exam- 

 ples of the Domestic Cat." Am. Jour. Anat., vol. vi, no. 3, 1907, Abstr. Anat. 

 Record, vol. i, p. 30. 



" G. S. Huntington and C. F. W. McClure "The Interpretation of Variations 

 of the Postcava and Tributaries in the Domestic Cat, based on their Develop- 

 ment." Am. Jour. Anat., vol. vi, 1907, Abstr. Anat. Record, vol. i, p. 33. 



