SUMMARY AM) CONCJ.rSIOXS 



In concluding this part of the record of observations on the on- 

 togeny of certain axial systemic lymphatic channels in nubryos 

 of the domestic cat, I desire very briefly to contrast the results of 

 this investigation with the tenets of the theories of nKuuiiialian 

 lymphatic development divergent from the views here expressed. 

 This is not done for the purpose of inciting or ])rolonging a con- 

 troversial discussion. As far as I am personally concernrd. ((ui- 

 troversy is at an end, because I believe that I have furnisiied ])osi- 

 tive evidence of the correctness of the opinion whicli 1 have 

 maintained during the past six years, from the tune on when my 

 investigations first warranted definite conclusions. The results 

 given in previous publications, and more in detail in the i)i('ceding 

 pages, afford to me a sound basis for interpreting my findings of 

 adult as well as of embryonic organization of the lymphatic system 

 both in mammals and in the other vertebrate classes. Conse- 

 quently, until these results are successfully accounted for on an 

 equally broad and phylogenetically consistent hyjiothesis elitTer- 

 ing from my own interpretation, and until the deductions leased 

 on them are shown to be erroneous by equally full and conii)re- 

 hensive proofs, I shall rest quite satisfied with the ])()sition 1 liave 

 reached on this question. 



It may, however, serve a useful purpose in enabling scientific 

 men in general to draw their own conclusions, if the facts here 

 offered are contrasted in a final review with the divergent theories 

 of lymphatic development which have been propounded in the 

 last decade. 



In regard to the view which supposes the mammalian lymphatic 

 system to arise by an outgrowth or bud from one or more sacs of 

 venous origin and thence to extend by a continuous centrifugal 

 process from centre to periphery, terminating in closed lyniiihatic 

 capillaries, I find little to say. 



1.53 



