DEVELOPMENT LYMPHATIC SYSTEM IN AMNIOTES 287 



into the heart? Do they then reverse their direction and. grow 

 out toward the periphery? What histogenetic evidence has 

 Fedorowicz in support of the supposition that they thus grow 

 until they unite with the longitudinal dorsal and ventral lym- 

 phatics of the tail? Also, where do these vessels come from? 



Fedorowicz's work, as above stated, suffers from the attempt 

 to correlate his results to the divergent views of previous investi- 

 gations. Thus he says (p. 296), in speaking of the earliest lym- 

 phatic anlages as observed by him: ''Freilich entwickeln sie sich 

 an den Herzen in anderer Weise, als dies Kolliker, Golubew, 

 Rouget und Clark beobachtet haben." Then he continues: 

 '^Doch wurden die unzweifelhaft richtigen Beobachtungen dieser 

 Forscher erstens an lebenden Material und ferner an den feinsten 

 Lymphgefassen ausgefiihrt." 



It is difficult to see where Fedorowicz finds grounds for recon- * 

 ciling his results with those of the investigations he quotes. 'Two 

 sets of observations cannot possibly contradict each other arid 

 still both be right, provided they cover the same premises. If 

 an observation on fixed material differs from one made on living 

 material, then one of three things has happened: Either the 

 observation on the fixed material is correct and the observation 

 on the living material is wrong, or the observation on the fixed 

 material is wrong and the observation on the living is correct, 

 or, lastly, both the observations on the fixed material and the 

 observation on the living material are wrong. Only one fact 

 appears to be absolutely certain, viz., the observation on the 

 fixed material and the observation on the living material can- 

 not possibly both be correct if they furnish fundamentally dif- 

 ferent conclusions. Still, in spite of this conflict with authority, 

 Fedorowicz finds the earliest anlages of the lymphatic vessels in 

 cellstrands, which then acquire a lumen by the development of 

 intercellular spaces, and subsequently make secondary connection 

 with the lymph hearts. 



These observations, coming from Hoyer's laboratory, which 

 has for so long maintained the centrifugal outgi'owth of the lym- 

 phatic system from the veins, are encouraging indications of a 

 coming impartial attitude on part of the Polish investigators. 



