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Blisnianskäja believe that our Lateral 1, the so-called "eparterial 

 or tracheal bronchus", is a derivation of our Lateral 2, which wanders 

 up on the stem bronchus or trachea, the others look upon it as an 

 independent and unpaired element. Narath and Blisnianskäja regard 

 the other chief bronchi as secondary derivatives of the lateral group 

 as "accessory" in the sense of Aeby. Willach looks upon the ventral 

 and median groups as accessory, that is to say, derived from the 

 lateral and dorsal bronchi respectively, while Robinson thinks the 

 chief bronchus of the ventral series. Ventral 2 (the Bronchus infra- 

 cardiacus) is ontogenetically independent, but phylogenetically acces- 

 sory. The latter describes the origin of the medial bronchi, his dorso- 

 internal group, from the dorsal by a process of progressive splitting 

 of the first medial branch of the dorsal bronchi until it comes to 

 have an independent origin on the stem, a view which is advanced 

 in greater detail by Narath. 



All of the arguments of Narath and Blisnianskäja concerning 

 the derivation of the ventral, dorsal and medial series either primarily 

 or secondarily from the lateral bronchi are quite unconvincing, for 

 like the support, which Narath brings from comparative anatomy, 

 are capable of a simpler explanation, namely in the wide variation in 

 the position of the buds and the power of one bronchus substituting 

 for another. These two factors which I have followed in detail in the 

 pig's lung, will explain all of the conditions in the adult tree which 

 led first Aeby and then Narath and their followers to look upon 

 the ventral and medial groups as derivatives of the lateral series. 

 It may also be well to call attention to Hesser's pointed criticism of 

 Narath's view when he remarks that the lateral buds of Narath 

 when they have only reached the development of a low round cone 

 with a broad base, represent the anlagen of four different branches, 

 namely the dorsal, lateral, ventral and medial bronchi which must 

 isolate themselves and take their places on the stem. And lastly, we 

 cannot help noting the lack of the one convincing argument which 

 should come from comparative anatomy consisting in a primitive lung 

 that possesses only lateral bronchi. 



Furthermore, the series of schematic figures, which Narath gives 

 to show the origin of the medial from the dorsal bronchi are ob- 

 jectively correct and agree with the conditions found in the pig's lung 

 not only in the embryonic stages but in the adult tree as well. He 

 finds the first median division of the dorsal bronchus as one decends . 

 from D. 2 to D, 5, is placed successively nearer the stem bronchus " 

 until, at the latter point buds are seen on the dorsal and medial 



